Swift Closures Quick Reference: Part 1

October 18, 2014 Leave a comment

Blocks/Closures are confusing!  They’re confusing because its a bit abstract.  Most tutorials cover how a block is declared and used.

Sometimes blocks or closures can me even more confusing…

A block is a bunch of code wrapped up in a {}.

You can 2 either of 2 things with them:

A.  You can assign that block of code to a variable. (this is where completionHandlers, also a confusing concept, fit in)

B.  You can use that block of code directly

Let’s take a look at assigning it to something.  No doubt you have seen a construct like:

var someName = “Mars”

or

var hisAge = 39

This would be considered hardcoding that value to the variable.

Now surely you have seen a function that does something more practical such as calculate or do something in order to return a value.  In the case of someName, well, we could fetch it from a list of users in a web service database.  In the case of hisAge we could calculate it.  Either process would occur in a function.  So we could instead of hardcoding a value, say:

var someName = getHisName()

or

var hisAge = getHisAge()

Well what we are doing here is actually ‘passing a block of code’ to a variable already.  Sorta.  We could somehow imagine that:

var hisAge = getHisAge() { //all the code inside getHisAge function }

which translates to:

var hisAge = { //all the code inside getHisAge function }

Ok, so that’s more or less what a block or closure is.

Where it gets weird, or complicated but just because of the way it looks is when they are passed to functions. You could go ahead and say something like:

func thisIsSomeFunction () -> () { //code }

which is a function that doesn’t take parameters and returns nothing.  Let’s give it a parameter:

func thisIsSomeFunction (aParameter:pType) -> () { //code }

This takes aParameter of pType.  Now replace that parameter with hisAge:

func thisIsSomeFunction (hisAge) -> () { //code}

Now let’s replace hisAge for what it stands for (which is { //all the code inside getHisAge function } )

func thisIsSomeFunction (  () -> () ) -> () { //code}

where () -> () stands for whatever hisAge is equal to, which is the getHisAge function…

Of course the getHisAge function must at least return something, an age, which would typically be an Int:

func thisIsSomeFunction (  () -> (Int) ) -> () { //code }

It would be wise to calculate someone’s age using at least his date of birth, so:

func thisIsSomeFunction (  (NSDate) -> (Int) ) -> () { //code }

Ok so our getHisAge function is in blue and it is passed into this new function.  Now it would be nice to pass in the original getHisAge code which would fit somewhere in here:

func thisIsSomeFunction (  (NSDate) -> (Int) {//getHisAge code} ) -> () { //code }

So for this purpose we have the keyword “in”:

func thisIsSomeFunction (  (NSDate) -> (Int) in {//getHisAge code} ) -> () { //code }

Hope you enjoyed it.  See you in the next part!

Categories: Iphone Developer

Swift is Confusing: Classes, Structures, Designated Initializers, Instance Methods, Type Methods, Functions, Methods, Convenience Initializers & External Parameter Names

October 10, 2014 Leave a comment
Swift is Confusing: Classes, Structures, Designated Initializers, Instance Methods, Type Methods, Functions, Methods, Convenience Initializers & External Parameter Names

Swift is Confusing

Class vs Structs

Both: Store values, initialize, subscripts, extensible & protocol

Class can inherit, de-initialize, reference counting & typecast

Functions vs Methods

Methods are FUNCTIONS INSIDE A CLASS

Functions can be inside or OUTSIDE A CLASS!

Cannot use functionName(param1,param2) to call a function declared inside a class {}

Methods:

  1. It is implicitly passed the object for which it was called
  2. It is able to operate on data that is contained within the class

Instance Methods vs Type Methods (Instance Method vs Class Methods I think)

Methods are functions that are associated with a particular type. Classes, structures, and enumerations can all define instance methods, which encapsulate specific tasks and functionality for working with an instance of a given type. Classes, structures, and enumerations can also define type methods, which are associated with the type itself. Type methods are similar to class methods in Objective-C.

  • class Counter {
  • var count = 0
  • func increment() {
  • count++
  • }
  • }
  • let counter = Counter()
  • counter.increment()

vs

  • class SomeClass {
  • class func someTypeMethod() {
  • // type method implementation goes here
  • }
  • }
  • SomeClass.someTypeMethod()

Class Factory vs Initializer

This is not particular to Swift but may come up in searches.  A Class Factory method is what was know in ObjC as factory methods and I even saw them references as convenience methods or constructors.  These are instead of:

NSArray *someArray = [[NSArray alloc] init]];

they would be:

NSArray *someArray = [NSArray arrayWithObjects:@"One", @"Two"];

Another example:

  • UITableView *myTableView = [[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStyleGrouped];
  • let myTableView: UITableView = UITableView(frame: CGRectZero, style: .Grouped)

ObjC class or factory methods get mapped as convenience initializers in Swift.  So:

  • UIColor *color = [UIColor colorWithRed:0.5 green:0.0 blue:0.5 alpha:1.0];

gets translated into this:

  • let color = UIColor(red: 0.5, green: 0.0, blue: 0.5, alpha: 1.0)

Designated Initializer vs Convenience Initializer

A designated initializer calls its superclass’ init and defines all values added by the self class.  Unless explicitly provided, a class inherits a super initializer from its superclass.

Any other convenience initializer calls self.init and have the convenience keyword before the init keyword.

Initialization must be done in order; own properties, super, super properties.

Initializers & Optionals in one :-)

  • class SurveyQuestion {
  • let text: String
  • var response: String?
  • init(text: String) {
  • self.text = text
  • }
  • func ask() {
  • println(text)
  • }
  • }
  • let beetsQuestion = SurveyQuestion(text: "How about beets?")
  • beetsQuestion.ask()
  • // prints "How about beets?"
  • beetsQuestion.response = "I also like beets. (But not with cheese.)"

Default Initializers

  • class ShoppingListItem {
  • var name: String?
  • var quantity = 1
  • var purchased = false
  • }
  • var item = ShoppingListItem()

All non-optional values are supplied with a default value and it is a Base Class (because it doesn’t have a super class)

Diagram:

class A {
    var x: Int
    convenience init() {
        self.init(x: 0)
    }
    init(x: Int) {
        self.x = x
    }
}

where init(x:Int) is the designated initializer and any other must have the convenience keyword.

class B: A {
    var y: Int
    convenience init() {
        self.init(y: 0)
    }
    convenience init(y: Int) {
        self.init(x: 0, y: y)
    }
    init(x: Int, y: Int) {
        self.y = y
        super.init(x: x)
    }
}

Parameter Names / Externals / The first

//Default: First Parameter is the local parameter (don't need to specify it), the rest are external parameters
    func greet (name: String, day: String) -> String {
        return "Hello \(name), today is \(day)."
    }
greet("John", day:"Monday")
    //Use Hash symbol to make the First parameter as external parameter
    func greet2 (#name: String, day: String) -> String {
        return "Hello \(name), today is \(day)."
    }
greet(name:"John", day:"Monday")

Swift Optionals Quick Reference

September 19, 2014 Leave a comment
Swift Optionals Quick Reference for Newbies by Santiapps.com

Swift Optionals Quick Reference for Newbies by Santiapps.com

Optionals confuse me so I wrote this post and hope it can be of some help.

OPTIONALS

Takeaway #1: Optionals are used to declare a variable but are not assigned a value at start

Takeaway #2: Optionals contain a Some or None value, they DONT contain a String or Array or whatever else.

Takeaway #3: Therefore we MUST unwrap the value of an Optional to see what the prize is :-) In other words, to access its value!

Takeaway #4: DECLARATION OPTIONS

A) Using the following syntax: var someVar? – You will mostly use this…

B) Using “var someVar!” <Implicitly unwrapped> – Unfortunately UIKit & other Apple frameworks will use a lot of these…

… NEED TO EXPLORE THE DIFFERENCE BETWEEN ? and ! declarations…

Turns out you can declare a variable as an implicitly unwrapped optional if you know it will, at some point, be non-nil.  So for example, in this SO post (http://stackoverflow.com/questions/24006975/why-create-implicitly-unwrapped-optionals) they talk about have viewDidLoad in a view controller call a setter upon load:

var screenSize: CGSize?

override func viewDidLoad() {

super.viewDidLoad()

screenSize = view.frame.size

}

We know that screenSize will be filled because viewDidLoad WILL be called.  Then later we do:

@IBAction printSize(sender: UIButton) {

println(“Screen size is: \(screenSize!)”)

}

We know screenSize will have a value if its ever called.  So we can instead declare it as an implicitly unwrapped optional with a ! instead of a ? in the initial var declaration.  But don’t sweat this so much right now.

Takeaway #5: ACCESS (UNWRAPPING) OPTIONS 

Takeaway #6: Method 1: Traditional (Risky): if var != nil and then access it inside the if block.

if yourOptionalTypeOrOptionalReturningFunction != nil {

doSomethingWith(tempOptional!) || setSomeValue = tempOptional!

}

But to access it you have to unwrap the present :-)  To do this you use the bang operator !  Whenever you use the ! you are ‘force unwrapping’ a variable, which means it will open it no matter what.  If nil is in there…KABOOM!  Bye bye Moose & Squirrel!  So you better have checked before hand.

Takeaway #7: Method 2: Optional Binding (aka:”if-let nil check”) (Safer): This means you use:

if let tempOptional = yourOptionalTypeOrOptionalReturningFunction {

doSomethingWith(tempOptional) || setSomeValue = tempOptional

}

This is more safe because it checks first or peeks in the box so to speak.  Thus you can use the variable without unwrapping.

< If you remove default value from a ? and have a ! to access it in code, your code will fail if-check will go to else.>

Takeaway #7: Method 3: Implicitly Unwrap: Uses ! operator (assumes var contains some value). But remember from Method 1, if nil, KABOOM!!!!!!

<If you remove default value from a ? and have a ! to access it in code, you get runtime crash = error = “can’t unwrap optional.None”>

Takeaway #8: Optionals unwrapped using? – This one is still kinda confusing to me. Has to do with optional chaining and inline downcast syntax I believe.  It means that when you have many optionals.  Let’s assume you have a class with 2 optional variables, name? and price?  Let’s pretend you write a function that creates a new Stock() class object and must therefore set name & price variables for it.  We would first have to check if one is set and then the other:

if let someName = stock.name {

if let somePrice = stock.price {

//now we can do something with price…

}

}

This would get messy.  So we chain them into a single statement like so:

someVariableWeWantToSet = stockName?.stockPrice

Takeaway #10: Many ObjC framework objects are optionals? and many are implicitly unwrapped! when passed into functions because they will start out as nil (UILabels, MKAnnotationViews or MKPolylines) but we know they will eventually get filled in because that’s why we put them there in the first place:

MKAnnotationView!

MKAnnotation!

UIControl!

MKPinAnnotationView!

MKMapView!

Takeaway #11: When we have something like an MKAnnotation! is received in a function as annotation. If we wish to use its super class properties, we must be inline downcast to while if-let checking. Once inside we can implicitly (force) unwrap MKPinAnnotationView! because we know since the annotation exists, it will have a view. For example, in this method:

func mapView(mapView: MKMapView!, rendererForOverlay overlay: MKOverlay!) -> MKOverlayRenderer! {

if let polylineOverlay = overlay as? MKPolyline {

let renderer = MKPolylineRenderer(polyline: polylineOverlay) renderer.strokeColor = UIColor.blueColor()

return renderer

}

return nil

}

We can interpret that funky as? as follows: “If when I get the variable overlay and unwrap it, it downcasts successfully to a MKPolyline && I get a value (not-nil) then put it into polylineOverlay & continue…” Hope this helps…

Why, oh Why, did Apple take away ARC just to give us Optionals!?

September 12, 2014 Leave a comment

I’m having trouble understanding optionals so here is a shot at explaining them. :)

var thisIsAnInt: Int

Simple, this is an Int variable declaration.

var couldBeAnInt: Int?

This on the other hand is an optional variable declaration.

This optional declaration doesn’t mean: “this is an int, which is optional”.

It reads more like: This is an OPTIONAL variable.  It’s a type of variable in and of itself.  Its NOT NECESSARILY an Int.  It just may or may NOT contain an Int”.

Woah!

Ok so what is it for and when do you use it.  Well that part seems simple enough:

If that variable can or could or may be nil at some point, it’s an optional.

If the variable will always have a value, it will never be nil, its NOT an optional.

Don’t be misled by this simplicity.  Some variables can start out as nil and receive a value at some point.  What then?

Well it turns out there is a sort of table, if you will:

  1. Can NEVER be nil (or if it IS, its a bug) = non-optional variable….you know, the regular kind
  2. Starts out nil but NEVER ends up nil after init (or if it is, its a bug) = implicitly unwrapped optional
  3. Nil value has meaning and is expected (if it is, its NOT a bug) = optional

Yeah, thanks for confusing me :S

Here is another way around it:

var perhapsInt: Int? //this is perhaps an Int
perhapsInt = 1 //here we assign it an int
if perhapsInt != nil { //now we check to see if its nil before using it
     let intString = String(perhapsInt!) //IF it isn't, then we can access it by using !
     println(intString)
}

you can also check for that in a different way:

var perhapsInt:Int?
perhapsInt = 1 
if let actualInt = perhapsInt {
     println(actualInt)
}

Here is the kicker:

var perhapsInt: Int?
let definiteInt = perhapsInt ?? 2
println(definiteInt) // prints 2
perhapsInt = 3
let anotherInt = perhapsInt ?? 4
println (anotherInt) // prints 3

And it gets trickier what with ?? and variable != nil.  So let’s throw everything out the window and start anew.  Let’s define a function we might actually be interested in:

Assume we have an array of locations:

let errorCodes = ["100","200","300","400", "500"]
func findErrorCode (code : String, errorCodes: [String])-> String {
for tempCode in errorCodes {
     if ( tempCode == code) {
     return code
     }
}
return ""
}

This is a function we wrote to find a particular code inside an array of possible error codes.  We call it by passing it in a code and the array of possible codes.  If we pass it a code that is NOT in the array, let’s say “700”, then the “internal if” will not evaluate to true and we must return nil.  We must return nil because otherwise, because the function is meant to return a String (the name of the matched code) && that “if block” didn’t hold true, you get a compiler error because we are not being exhaustive.  This means, if we pass the function a value that IS in the array, great, we will get a ‘return code’.  However, if we pass it a value that is NOT in the array, the function would not be returning anything.  So we NEED to return something for it to work.

We could return an emply value but consider the following.  Let’s say we wish to display that code returned in the console, via println (or plot it on a map of servers for example).  The point being that we need to do something with the returned code:

if findCode("700", errorCodes) {
	plotOnMap()
}

So how do we account for such a possibility?  We need to define the return value of the function findCode as an optional.  To do this we add this to the variable “?”.  Here is what the function would look like:

func findCode (code : String, errorCodes: [String])-> String? {
for tempCode in errorCodes {
     if ( tempCode == code) {
          return code
     }
}
return nil
}

Now we can actually return a String value, maybe, or we could be returning an Optional value.

Great, now let’s asume the plot function looks like this:

func plotOnMap (code: Int) -> () {
     println("This line of code magically plots the code on a server map :)")
}

Ok so now we can say

let receiver = findCode("200",errorCodes)
if receiver {
	plotOnMap(receiver);
}

The issue is that the value returned by findCode, is Optional.  So the value of receiver will be optional.

This is what is called “implicitly defined optional“.  We have implicitly defined receiver to be an optional because the return of the function is an optional itself.

We also have another issue, plotOnMap() takes an Int, not a String.  So we have actually defined receiver as:

let receiver: String? = findCode("400",errorCodes) // inferred type String?

Notice we have defined it as String?, not String.  This means receiver can hold a String or a nil, because its being defined as an Optional type, not a String type.

So what can we do?  We can ask it for a value only if it HAS one:

let receiver = findCode("400",errorCodes) 
if receiver {
	plotOnMap(receiver!) // We use of the ! operator to unwrap the value to String
}

This would indeed fix the problem.  You have solved the possibility of an optional in a function you wrote yourself.  But there is always the other case, values returned by functions you DIDNT write!  Ugh!  Remember I mentioned that our plotOnMap() takes an Int, and not a String?  And we are in fact unwrapping an implicitly defined variable (called receiver) into a String (cause that’s what the function returns?  Well we need to convert it into an int, which is simple in Swift, just say string.toInt().  This means we have to do this:

if let receiver = findCode("400",errorCodes) {
	plotOnMap(receiver.toInt())
}

But if you jump to definition on toInt(), you will notice that it also returns an optional.  So we would need to do something more convoluted:

if let receiver = findCode("400",errorCodes) {
	if let receiverErrorCode = receiver.toInt() {
		plotOnMap(receiverErrorCode)
	}
}

which is quite confusing.  So there is a Swift syntax which let’s you condense this into:

if let receiverErrorCode = findCode("400",errorCodes)?.toInt() {
	plotOnMap(receiverErrorCode)
}

It would be prudent just to add an else to the if to be safe :)

iOS : Swift : Blocks = Closures

September 3, 2014 Leave a comment

Closure on closures

Closure on closures

I’ve never really liked blocks in ObjC.

When Swift came out it made things more complicated for me because I’ve never really liked C either.

Finally when I had to deal with closures in Swift, well that’s just gonna piss a lot of people off!

After a few days reviewing tons of material online, and I mean TONS!  I came to understand this:

The only C-like exposure I had prior to ObjC was a little PHP.  So that allows me to understand a function, which is the equivalent of a method in ObjC:

DECLARING

func sayHello( ) {

     println(“Hello World”)

}

CALLING

sayHello( )

RESULT

Hello World

Even if you didn’t have any exposure to C or PHP or some other “not-so-friendly” language as ObjC, you can surely understand that

  1. The function is called sayHello
  2. That it takes no input-parameters because the ( ) is empty
  3. That it has no return type because it returns nothing since its missing the keyword “return” inside of it :)
  4. And that all it does, instead of returning a value, is print out Hello World

Just to clarify, let’s look at a function with a return value:

DECLARING

func sayHello () -> String {

    var result = “Hello World”

    return result

}

CALLING

var whoAreYou = sayHello()

RESULT (value of whoAreYou)

Hello World

As you can see here, we actually return a value from this function, which we can assign to a variable.  I had to assign it to a variable so that it made sense to actually return a value from a function.  

So we added an output-value to an otherwise plain vanilla function.  Now lets go for the next kind of function, plain + output + input:

DECLARING

func sayHello (friendOne:String) -> String {

    println(“Hi \(friendOne)”)

    var result = “Hello, ” + friendOne

    return result

}

CALLING

var whoAreYou = sayHello(“Marcio”)

RESULT (value of whoAreYou)

Hello, Marcio

Great!  So you’ve got functions covered:

  • Plain void functions
  • Returning output-value functions
  • Input-Paramter, returning output-value functions

CLOSURES (or blocks from ObjC)

There really is no simple way to explain it in a few words.  But the first thing that stands out from a closure or block, is that IT IS a function, yes!  But it can be passed around like a variable.  So let’s take a look:

var someVariable: String

There, we just declared a variable of type string.  Let’s declare another variable:

var someOtherVariable: ( ) -> ( ) = { }

There, we have just declared another variable, of type…? :s

Simply combine the concepts:

variable = function

And we know that a function is:

function = functionName (input-parameter) -> (Output-value) {some code}

So now say:

variable = function = functionName (input-parameter) -> (Output-value) {some code}

Now drop the middle “function” :)

variable = functionName (input-parameter) -> (Output-value) {some code}

If you don’t want the function to have a name, because you are assigning it to a variable anyway, so you can just call it by calling the variable:

variable = (input-parameter) -> (Output-value) {some code}

Hey, that looks a lot like what we had above:

var someOtherVariable: ( ) -> ( ) = { }

Cool!  So what does it all mean Basil?

The important thing is that you will use closures in Swift.  I was working with Parse SDK the other day and I ran into this in Xcode:

Get closure on Closures

Get closure on Closures

This is the first stage of Autocomplete which you may already be familiar with.  It’s telling you this:

Void saveInBackgroundWithBlock(block: PFBooleanResultBlock!(Bool, NSError!) -> Void)

You already know what this means, its just a function/method that takes a block as a parameter.  

This function returns Void, according to the left Void in that line.  

Let’s say that the method is called saveInBackgroundWithBlock ( X ) and it takes 1 parameter, X, where X is a block.

The block is defined as a variable “block:” and its called PFBooleanResultBlock!

It has 2 output-values Bool & NSError.

Now you know how to fill it in.  But wait, there’s more…if you call in the next 15 minutes :-)

But seriously, Xcode now has something new.  Check it out!  To select that method in the image above, you hit Enter.  This spits out the method signature in the Editor window and expects you to fill in the rest…THE NERVE!  Luckily, you can hit Enter again while that blue selection is highlighting the block and that will give you this:

tah dah!

Get closure on Closures

Get closure on Closures

Now that’s better!  This is Xcode’s new second stage Autocomplete.  Its telling us that the block is defined by { } and it takes 2 input-parameters and returns a Void.  That new “in” keyword serves to separate the return (which is in this case, Void) from the actual code block which follows.

So you can call closures like so:

object.saveInBackgroundWithBlock {succeeded, error in

//some code

}

OR

object.saveInBackgroundWithBlock { (succeeded, error) -> Void in

//some code

}

 OR

object.saveInBackgroundWithBlock( { (succeeded:Bool, error:NSError!) in

//some code

})

OR

object.saveInBackground( { (succeeded:Bool, error:NSError! ) -> Void in } )

OR you can assign it:

var someVar: () -> () = {              

println(“Hello World”)

}

Enjoy!

 

EDIT: In brief:

How to write or declare closures:

{ (succeeded: Bool, error: NSError?) -> Void in /* code */ }
{ (succeeded: Bool, error: NSError?) in /* code */ }
{ (succeeded, error) in /* code */ }
{ succeeded, error in /* code */ }
{ /* code using $0 for succeeded and $1 for error */ }

How to pass a closure:

object.saveInBackgroundWithBlock({ /* closure */ })
object.saveInBackgroundWithBlock() { /* closure */ }   // Only if closure is last arg
object.saveInBackgroundWithBlock { /* closure */ }     // Only if closure is only arg

iOS7 Custom Transitions

August 26, 2014 Leave a comment
iOS7 Custom Transitions

iOS7 Custom Transitions

iOS7 Series –Custom Transitions

There is a hierarchy of actors you need to visualize here.  It goes a little something like:

  1. A TransitioningDelegate
  2. An AnimatedTransitioning
  3. A ContextTransitioning

The VC you start out with and that will call the transition will adopt the first protocol, the TransitioningDelegate Protocol.  The purpose of doing so is to obtain the authority to manage the entire transition process.

You will then create a Transitioning class which we can call the Transition Manager.  This class will adopt the AnimatedTransitioning protocol.  The purpose of this protocol is to animate the transition.

The Transition Manager class receives all the necessary information from the Transitioning Context (a protocol adopted by a class you wont really see) and it sends that info to the TransitioningDelegate in order for it to call the shots.

The process itself is quite simple.  We create a Transition Manager class, which adopts the AnimatedTransitioning protocol as stated above.  Then we instantiate this class and call its methods from our initial view controller, who has adopted the TransitioningDelegate protocol in order to call the shots.  Voila, our VC calls the transition for us.

So create a subclass of NSObject and call it what you wish, I called it PinRotatingTransitionManager.  Of course make it adopt the AnimatedTransitioning protocol like so:

<UIViewControllerAnimatedTransitioning>

There are 2 methods you must implement in order to adopt this protocol.  The first one is:

//Define the transition duration

-(NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext{

return 1.0;

}

As you can see this simply states how long the transition will last.  It returns a value of type NSTimeInterval and takes in the transition context.

The second method is for describing the animation and it’s a bit long so let’s go one step at a time:

//1. Get current state

UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];

UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

CGRect sourceRect = [transitionContext initialFrameForViewController:fromVC];

First we get some values for the current state; who is our fromVC, who is our toVC and what is the relevant frame of our current, fromVC.  Remember we are transitioning between two vcs.  The one we are in is called the fromVC or initialVC or if you prefer to keep the original iOS lingo, our sourceVC.  The second one is called our toVC or finalVC or destinationVC.

We need to get a reference to both of them (basically to say THIS vc will do this and THAT vc will do that!).  And of course we need to know the frame we are starting from.

//2.Settings for the fromVC ……………………….

CGAffineTransform rotation;

rotation = CGAffineTransformMakeRotation(M_PI);

fromVC.view.frame = sourceRect;

fromVC.view.layer.anchorPoint = CGPointMake(0.5, 0.0);

fromVC.view.layer.position = CGPointMake(160.0, 0);

We create a rotation transform which will rotate anything by M_PI.  Then we set our fromVC frame to the sourceRect, we define an anchor point for it and a position for it.

//3.Insert the toVC view………………………

UIView *container = [transitionContext containerView];

[container insertSubview:toVC.view belowSubview:fromVC.view];

CGPoint final_toVC_Center = toVC.view.center;

Now we need to do something quite important…get a container view to put everything into in order to run the transition.  To that container view we must add the toVC, because the fromVC is already added for us.

//4.Insert the toVC view………………………

toVC.view.center = CGPointMake(-sourceRect.size.width, sourceRect.size.height);

toVC.view.transform = CGAffineTransformMakeRotation(M_PI/2);

Now we set the toVC’s center point and apply the transform created.

And finally we perform the animation:

//5. Animate..

[UIView animateWithDuration:1.0

delay:0.0

usingSpringWithDamping:.8

initialSpringVelocity:6.0

options:UIViewAnimationOptionCurveEaseIn

animations:^{

//Setup final params of the views

fromVC.view.transform = rotation;

toVC.view.center = final_toVC_Center;

toVC.view.transform = CGAffineTransformMakeRotation(0);

} completion:^(BOOL finished) {

//When done call completeTransition

[transitionContext completeTransition:YES];

}];

This is quite simple.  We define some parameters for the animation and call a block which applies the rotation and center etc.  Once complete we call completeTransition which is mandatory.

Now run your app and you should have a very nice transition where the fromVC slides left and the toVC rotates down into place.

 

Neat huh!

Business of iOS Apps

August 8, 2014 1 comment

iOS apps business by Santiapps.com Marcio Valenzuela

iOS apps business

I keep reading articles or watching videos of iOS businesses who made it and they share their wisdom of the Common 10 Mistakes iOS developers make. Guess what? Most of those mistakes, although they are worded as developer concepts, they are really business concepts.

Common Mistakes: Don’t need a marketing guy. Don’t need a business guy. Don’t need a business perspective. Usually worded as, I thought I would get rich quick, or Im looking for a one hit wonder, or Im a great programmer and I thought that was enough.

Well guess what, if you are going to sell something and make more than 99c for it, its gonna need a Business Plan. But don’t fret, it doesn’t mean you need an MBA to help you come up with a business plan. If you are a level headed guy-or-gal, you should be ok. You just need to know what to put down on paper. You WILL need a plan if you are going to be selling something more than lemonade :)

Its a plan, take out the word ‘business’ if you don’t want to. But just think about this, Steve Jobs wasn’t the business plan type. He wanted to run his company the way he wanted to. So they kicked him out of his own company because of that. True, they begged him to come back, but Jobs had learned a thing or two about making plans. That combination took Apple to the top.

So let’s just call it a plan, because you will jot down ideas to help you organize what you need to do. Let’s add the word operating, because it will be a hands-on kind of plan. And if you wanna get fancy, throw in the word Strategic, because it will take some key ideas to put this plan into action.

Your ‘Strategic-Operating-Plan’

You need to analyze what you have and don’t have. Did you see the movie Public Enemy with Hackman and Smith? Well, if they’re big, you’re small, they’re slow and you’re mobile. To know what you can be, you gotta know what you are right now and what you’re missing.

(SWOT)

1) Know your Strengths

2) Accept your Weaknesses

3) Spot market Opportunities

4) Identify any Threats

Once you know what you have and don’t have, you probably realize you have programming skills but no selling skills. This is typical and it sucks! Guys who invented things (engine, nuclear fission, electricity) get credit, but they don’t get the ladies! Why? Cause they don’t get the moolah! You always see pictures of Einstein and Edison dying poor. But the Presidents and CEOs of companies who make cars, weapons and electricity are sitting pretty making millions every year plus bonuses and benefits.

Its a known fact, business types will always make the money while smarties slave away in a lab somewhere. You therefore need a plan to sell whatever it is you know how to make.

(Marketing Plan)

Product: The app you created is of what type? What exactly did you make and what can it do. It might seem silly, but write it down. More importantly, have others around you look at it, use it and write down what THEY think the product is and does. Did you make something you thought was cool or did you discover a need that nobody was covering quite that well? How many products can you make in a year? What kind of products will they be, will a client pull or will you push in the App Store? Your costs will vary whether its push or pull, but they won’t be zero I can promise you that!

Price: According to the type of app you made, how should you price it? Market vs Cost. You definitely need to cover your costs. But there are different types of costs. These are things you need to identify in your Strengths and Weaknesses. Your upfront costs or initial costs might be high but you can throw them all in a pile as part of the price.

If you took out a loan for 1 year of living expenses while you code (computer, internet, Apple Membership, electric bill, water bill, food, cellular etc) and ended up with a $25,000 loan, you can’t price your app at $25,500 :). You gotta know a little bit about finance such that you spread those costs out over a long period of time. If you made 1 app that sold for $1 (net) and expect 500 downloads a month, thats about $6,000 a year. That would pay off a no-interest loan in 4.1 years. But your loan payments may only be $100 a month. Think about how many apps you think you can put out a year because with 2 apps having 500 monthly downloads, your income doubles.

Place: Where will people buy it? AppStore, website, Facebook ads, Email, word of mouth. Your costs will vary depending on where you have to sell it. True, AppStore helps you lower the cost of marketing your app but it may not be the ONLY place you have to promote your app. A client-pulled app is safer in the sense that it will let you know your income upfront and significantly reduce your costs. Depending on how you defined your app, what needs it covers and how it is priced, you will decide the right place. Tech forums are not the right place for medical apps. A highly priced app would be better off at a local expensive supermarket with a nice banner than via massive emails to your friends.

Promotion: How will you promote it? InApp? iAds? As mentioned before, will this app be push or pull? That tells you where your app will be purchased and thus where you need to push it or have it be pulled. There are many ways to promote your app but in the end you need to monitor your promotions to know which ones are working our for you and which ones aren’t. That’s how you decide where to invest more money in order to promote it.

(Inherent offsync)

This is a heavy pill to swallow. Let’s define a few the kinds of concepts we have talked about and you know are required for app selling.

1) Programmers

2) Graphic Designers

3) Business

4) Sales

Like it or not, these are 4 very different types of people.

Programmers are introverted, mathematical geeks and abstract thinkers.

Graphic Designers are free spirited, un-organized rebels.

Business people are demanding, goal oriented doers.

Sales people are social, pushy creatures that hate work. Selling is not work, its their way of life.

These are mutually exclusive human traits. Ask any psychologist. This is basically why you can’t be a one-man show. You must at least be a two-man show where one programs and the other does business. That’s how most successful businesses are spawned, grown or nurtured. That means you would have to outsource graphic design and sales. Business management and operations really need to be in sync and thus should not be separated from each other and outsourced.

Graphic design is a bit easier to outsource than business-ing and programming. Sales can be ‘pushed’ or outsourced to many platforms nowadays either web, print or digital. You must still know what those platforms are, what their potential is, monitor them and grade them to see which ones work and which ones don’t. But you MUST measure everything and question why something is working (not working) the way it is (isn’t).

I don’t want you to read off with the wrong idea. Yes you CAN make it! Its just not gonna be easy, like everything in life, if you want it to be good, you have to work at it. Don’t be shy or scared of delegating and teaming up. Make sure you cover all angles, development (programming & design), business (operations & management) and sales!

Everyone must be a salesperson if they want to succeed!

Follow

Get every new post delivered to your Inbox.

Join 644 other followers