子视图不显示按钮或imageView

Question

作为另一个视图的子视图显示的视图在.Xib文件中具有以下设置。

以下是触摸呈现按钮时视图的显示方式。

以下是视图呈现方式的代码。

-(void)setUpImageSelectorView{
    ImageSelectorViewViewController *imageSelectorVC = [[ImageSelectorViewViewController alloc]initWithNibName:@"ImageSelectorViewViewController" bundle:nil];
    imageSelectorVC.delegate = self;
    imageSelectorVC.view.contentMode = UIViewContentModeScaleAspectFit;
    imageSelectorVC.view.clipsToBounds = YES;
    imageSelectorVC.imageView.image = img;
    [self.view addSubview:imageSelectorVC.view];
}

Answer 1

两个问题：

1. 这不是添加具有自己的控制器的子视图的正确代码。您应该使用自定义容器调用，例如：

   -(void)setUpImageSelectorView{
       ImageSelectorViewViewController *imageSelectorVC = [[ImageSelectorViewViewController alloc]initWithNibName:@"ImageSelectorViewViewController" bundle:nil];
       [self addChildViewController:imageSelectorVC];
       imageSelectorVC.delegate = self;
       imageSelectorVC.view.contentMode = UIViewContentModeScaleAspectFit;
       imageSelectorVC.view.clipsToBounds = YES;
       imageSelectorVC.imageView.image = img;
       [self.view addSubview:imageSelectorVC.view];
       // you probably should set the `frame` of this view, too
       [imageSelectorVC didMoveToParentViewController:self];
   }
   

   请注意addChildViewController和didMoveToParentViewController来电。

   当您要删除它时，请先致电[imageSelectorVC willMoveToParentViewController:nil]，当您完成删除所有操作后，请致电[self removeChildViewController: imageSelectorVC]。

   请参阅 View Controller编程指南（适用于iOS）中的Creating Custom Container View Controllers。有关为什么所有这些都非常重要的讨论（即，保持视图层次与视图控制器层次结构同步）请参阅WWDC 2011视频Implementing UIViewController Containment。

2. 如果您通过调试器运行应用程序并暂停执行（点击暂停按钮，而不是停止按钮），您可以通过键入

   来确认视图的布局

   (lldb) po [[UIWindow keyWindow] recursiveDescription]
   <UIWindow: 0x7fd91b542420; frame = (0 0; 375 667); gestureRecognizers = <NSArray: 0x7fd91b543000>; layer = <UIWindowLayer: 0x7fd91b5412d0>>
      | <UIView: 0x7fd91b5442d0; frame = (0 0; 375 667); autoresize = W+H; layer = <CALayer: 0x7fd91b5435c0>>
      |    | <_UILayoutGuide: 0x7fd91b5445e0; frame = (0 0; 0 20); hidden = YES; layer = <CALayer: 0x7fd91b537030>>
      |    | <_UILayoutGuide: 0x7fd91b544f40; frame = (0 667; 0 0); hidden = YES; layer = <CALayer: 0x7fd91b543850>>
      |    | <UIButton: 0x7fd91b446d50; frame = (5 285; 70 30); opaque = NO; tag = 12221; layer = <CALayer: 0x7fd91b4d8fb0>>
      |    |    | <UIImageView: 0x7fd91b57aa20; frame = (0 0; 70 30); clipsToBounds = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x7fd91b53b6f0>>
      |    |    | <UIImageView: 0x7fd91b51c040; frame = (0 0; 0 0); clipsToBounds = YES; hidden = YES; opaque = NO; userInteractionEnabled = NO; layer = <CALayer: 0x7fd91b539670>>
   

   有时会看到视图，但如果宽度/高度为零，则不会看到它（特别是如果你剪切到边界）。