Objective-C nil Outlets [英] Objective-C nil Outlets

问题描述

我有一个用于用户界面的类，有两个构造函数:

I have a class used for a user interface, with two constructors:

- (id)initWithBanner:(NSMutableArray *)banner {  
    if ( ( self = [super initWithNibName:@"UIBanner" bundle:nil] ) ) {
      // ... code...
    }
    return self;
}

- (id)initWithPreview:(NSMutableArray *)previews {
    if ( ( self = [super initWithNibName:@"UIBanner" bundle:nil] ) ) {
      // ... code...
    }
    return self;
}

在这两个构造函数中，我使用了两个出口，一个 UIPageControl 和一个 UIScrollView，与新的 XCode 4 链接.现在，如果我使用第一个构造函数 initWithBanner，一切正常(放置一个 NSLog(@"%@",bannerScroll) 给出了相关的出口描述)但是当我使用 initWithPreview 时，我的出口为零.这有什么问题?

Inside this two constructors, I use two outlets, a UIPageControl and a UIScrollView, linked with the new XCode 4. Now, if I use the first constructor, initWithBanner, everything works fine (putting a NSLog(@"%@",bannerScroll) gives the relative outlet description) but when I use initWithPreview, my Outlets are nil. What's wrong with that?

推荐答案

在实际加载笔尖之前不会设置您的插座，这发生在您的 UIViewController 的 view 属性被读取时.你实现 -viewDidLoad 方法来处理你的笔尖加载.另请注意，在 UIViewContoller 实例的生命周期中，视图和笔尖可以多次卸载和加载.

Your outlets will not be set until the nib is actually loaded, which occurs when your UIViewController's view property is read. You implement the -viewDidLoad method to handle when your nib has loaded. Also note that the view and nib can be unloaded and loaded multiple times during the life of your UIViewContoller instance.

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