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Normally an event, which is nothing but a message is fixed (set and implemented) in the same class or context, the function or procedure "caller". o in un UIViewController . For example if we add a button UIButton via code (programmatically), we can find our class in a UIView or a UIViewController . In both cases the task allocation and initialization of the button will be followed by the setting of target that should receive a message when it "clicks" the button, type:

Line 5 decides who the code shown above (the object) and what (method) "call" when our button is pressed. In the example above is also known that the pressure setting of the message is sent to the method onButtonClick implemented below, then part of the same context (or class). potremmo inviare il nostro messaggio ad un qualsiasi altro oggetto, posto quindi al difuori del contesto in uso. The first consideration is obvious that we can do, then, is that by altering the parameters self and action we can send our message to any other object, then place in the context difuori in use. : Here's an example: a class UIApplicationDelegate create a UIViewController :

associata al UIViewController stesso: The SplashScreenController exposes a method that allows you to animate the UIView associated with UIViewController same:

. The above code shows a method defined inside the class SplashScreenController type UIViewController . ) onAnimationFinished definito più sotto, facente parte sempre della classe SplashScreenController . It does nothing but animate the UIView animating it down, and when the animation is complete, call (send a message to itself - hence self ) onAnimationFinished defined below, is part of the class always SplashScreenController . , non saremo informati della fine dell'animazione: It follows that in our myAppDelegate , when we invoke the method animateBackgroundDown , we will not be informed of the end of the animation:

What we might want, instead, is to create a new version of animateBackgroundDown that tell me where to send the message at the end of animation, and which method to call. In practice we want to make sure to write in our class myAppDelegate :

, bensì in myAppDelegate . This time the method onAnimationFinished is not in the UIViewController , but in myAppDelegate . nel modo seguente: To do this simply change the method animateBackgroundDown in UIViewController as follows:

). Now we have a method that takes the "context" ( target ) and the method to call ( selector ). a qualsiasi altro “oggetto” / classe in grado di riceverlo. Now, when the animation ends, the message AnimationDidStop will be sent to myAppDelegate any other "object" / class that can receive it.

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CGRectMake() is a function (actually an inline # define) used a lot especially when you create graphics objects from code or user interface. o UIImageView . CGRectMake() restituisce una struct (struttura di tipo) CGRect : Its use is therefore often associated initialization components of UIKit , but also to simple UIView or UIImageView . CGRectMake() returns a struct (structure type) CGRect :

: Which in turn is composed of two different struct CGPoint and CGSize :

. That, in turn, again, contain types CGFloat or type float . If we analyze the code of CGRectMake () are:

It follows, therefore, that this piece of code:

It could rightly be written as:

Just to speed things up 'the code is running ...

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Xcode is a really good development environment, nice and full of details that make writing efficient code and pleasant. Among these is the ease of auto-complete when typing, especially when writing applications for Apple iPhone, where the frameworks are many and remember syntax and nomenclature company by a few.

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Using the Xcode Preferences you can set the behavior of the atmosphere during the debugging phase of an iPhone application. The default settings, in fact, are very uncomfortable when you try and try again an application, for example, after launching our application, you must manually open the Console window to see the output of various NSLog() . Xcode also lets the previous sessions in order to force us to clean the window by hand. Fortunately, you can solve the problem by acting on the Preferences:

As shown above, simply select an item from the menu on start to decide which debug window to open automatically at startup of our valid if (I & Debugger Console set but you can choose those that best suits you). On the right, then we find Auto Clear Debug Console, so you always start with a clean console.

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creato. I want to show how you can, easily and quickly extend a class UIView in a way that responds to a new initialization method contains additional code to customize the object UIView created. As some of you probably know, Objective-C does not support a single manufacturer as in other object oriented languages ​​(such as Adobe ActionScript or PHP 5). It 'can, in fact, create an instance of a class manually invoking different manufacturers (virtually infinite). . Normally we are used to create objects UIView with the classic initWithFrame . But imagine you want to create a new class of visual objects, from a UIView , with some additions, such as a built-in label. . Basically what we want is that instantiating our object it creates, as well as the UIView , an object of type UILabel . For example we might want to get to the end:

: To do this simply create a new class of type UIView and call ViewLabel :

At the time of the creation of our new class, we could use:

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As mentioned FirstApp iPhone: Guess the number - Part 1 we see how to make an application for the Apple iPhone without using Interface Builder! Indeed, we will eliminate physical files created by Interface Builder, Xcode wizard. At the end of this post, then, we have an application identical in all respects, to that achieved in the first part, with the difference that we will achieve all our visual components, including the main Window, completely to code.

The application already made, if you just want to download, is available on my Google Code repository:

• Browse sources
• Sources. Pdf (1005Kb)

I would like to point out immediately as the ZIP of this example weighing less than the last time!

We create the project

We start by creating our project SecondApp (to distinguish it from FirstApp), although this time choose Window-based Application:

Now let's delete everything related to Interface Builder. : eliminatelo anche dal file system, quindi selezionate Also Move to Trash . Delete the file MainWindow.xib , located in the folder Resources : also delete it from the file system, then select Also Move to Trash. nella casella Main nib file base name : Select then the file SecondoApp-info.plist and delete the reference to the MainWindow nib box Main base file name:

At this point we no longer have any Windows, at least through Interface Builder. , e modifichiamo la funzione main() in questo modo: So we open the file main.m , situated in Other Sources , and modify the function main() like this:

Open SecondAppAppDelegate.me then create the main Window in code:

You can already test the application, if you get a yellow window you did everything right!

, necessario solo se si usa Interface Builder. In the file SecondAppAppDelegate.h we can eliminate IBOutlet , only needed if you use Interface Builder. Also add here that our global variables, the last time we had entered in the Controller. Then modify the file SecondAppAppDelegate.h :

, in quanto non stiamo usando Interface Builder. Again we have prepared the method definition controllaNumero , like last time, but we have eliminated the indication IBAction , because you are not using Interface Builder.

We build the interface from code

It 'time to create code using all components of our interface. ed inseriamo il seguente codice: Let's go back to the file SecondAppAppDelegate.m , posizioniamoci before [mainWindow release] and insert the following code:

della scorsa volta, subito dopo il [mainWindow release]; inseriamo: Since the ' applicationDidFinishLaunching corresponds to viewDidLoad as last time, just after the [mainWindow release]; insert:

Now we can do is implement the method controllaNumero , which will be identical (apart from the prototype) to that used last time:

We're done!

Conclusions and considerations

, proprio perchè volevo lasciarlo il più semplice e snello possibile e, anche, per dimostrare che non sono elementi sempre necessari. This example does not make direct use of a UIView or UIViewController , just because I wanted to leave it as simple and streamlined as possible and, also, to show that the elements are not always necessary. However insert objects directly in the window can have some sense in this example and other sporadic contexts. portano comunque benefici in tantissimi altri casi, ein alcuni sono praticamente indispensabili; come avremo modo di vedere in futuro. The use of UIView and UIViewController bring benefits in many other cases, however, some are virtually indispensable ein, as we will see in the future.

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XCode is a very powerful and versatile and provides the programmer with many useful features and simple to use. When writing complex code, or at least articulated, it becomes important to organize your code so you do not waste time searching functions spread in long lines of code. After commenting, the first and most important thing to do, the environment XCode provides guidelines (nice) to improve the usability and legginilità within the development. One of these is the directive #pragma mark that becomes very useful in organizing groups of the code and methods.

In the picture below you can see the code part of my project PragmaTest :

The top dropdown menu allows you to list all the methods of our class. Now if we insert our method over the directive #pragma mark which has a syntax:

We get:

The first #pragma mark with a hyphen (-) inserts a separator line. The second is a text (label) to taste. You can add the following statement where you want, organizing the code as you see fit. You can enter more pragmatic lines, type:

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Available on the AppStore update to the 1.2 release of thefirst . Here are the release notes:

• Fully revised throughout the game's graphics, which is now much more pleasant
• Compatible with Apple iPhone 3.0
• Added sound effects
• Revised and improved the navigability of the game and instructions

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