代表 - 如何使用？ [英] Delegate - How to Use?

问题描述

我认为我理解代表背后的逻辑。我有更多的问题来使用它。涉及多少步？我必须使用现有的代表吗？或者我可以使用我的一个？

在我的例子中，我得到了AppDelegate创建了许多相同类型的视图（对象/视图控制器）。每个视图应该以某种方式调用AppDelegate上的一个方法来关闭它。当触摸视图中的按钮时，会发生这种情况。方法调用将包括视图（self）的引用。

到目前为止，我知道其他语言响应者，事件侦听器等。它们使用起来非常简单。

任何人都可以帮助我我刚刚在网络上发现了大量的代码。在Objective C中调用父对象不会那么难。

解决方案

我认为你应该使用 NSNotificationCenter

您 AppDelegate.m

pre> - （BOOL）应用程序：（UIApplication *）应用程序didFinishLaunchingWithOptions：（NSDictionary *）launchOptions
{
...
.. 。
[[NSNotificationCenter defaultCenter] addObserver：self selector：@selector（buttonPushed :) name：@ButtonPushedNotificationobject：nil];
}

- （void）applicationWillTerminate :( UIApplication *）应用程序
{
...
...
[[NSNotificationCenter defaultCenter] removeObserver：self];
}


这是在通知发生时将被调用的选择器（我们仍然是在 AppDelegate.m ）

   - （void）buttonPushed：（NSNotification *）notification {
 NSLog（@按钮推...）; 
} 
  

和 ViewController.m 当按钮推送（在方法内），您应该发布如下通知：

  {
 ... 
 [[NSNotificationCenter defaultCenter] postNotificationName：@ButtonPushedNotificationobject：nil]; 
 ... 
} 
  

I think I understand the logic behind a delegate. I got more the problem to use it. How many steps are involved? Do I have to use existing delegates? Or can I use my one ones?

In my example I got the AppDelegate that created many views (Objects / View Controllers) of the same type. Each view should somehow call a method on the AppDelegate to close itself. This would happen when a button within the view is touched. The method call would include the reference of the view (self).

So far I know from other languages responders, event listeners and so on. They are so simple to use.

Can anybody help me. I just found massive examples with a lot of code in the web. It can't be that hard to just call a parent in Objective C.

解决方案

I think you should use for this the NSNotificationCenter

in you AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
...
...
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(buttonPushed:) name:@"ButtonPushedNotification" object:nil];
}

- (void)applicationWillTerminate:(UIApplication *)application
{
...
...
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

this is the selector it will be called when the notification happens (we are still in the AppDelegate.m)

- (void)buttonPushed:(NSNotification *)notification {
NSLog(@"the button pushed...");
}

and in the ViewController.m when the button pushed (inside the method), you should post a notification like this:

{
...
[[NSNotificationCenter defaultCenter] postNotificationName:@"ButtonPushedNotification" object:nil];
...
}

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