ios - subview 不显示按钮或 imageView

Question

作为另一个 View 的 subview 呈现的 View 在 .Xib 文件中具有以下设置。

以下是当触摸呈现 View 的按钮时 View 的呈现方式。

这里是如何呈现 View 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 Controller 的 subview 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];
   }
   

   注意 addChildViewController 和 didMoveToParentViewController 调用。

   当您要删除它时，首先调用 [imageSelectorVC willMoveToParentViewController:nil]，当您完成删除所有内容时，调用 [self removeChildViewController: imageSelectorVC]。

   参见 Creating Custom Container View Controllers在 iOS 的 View Controller 编程指南中。要讨论为什么所有这些都如此重要(即，使您的 View 层次结构与 View Controller 层次结构保持同步)，请参见 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)，您可以通过键入确认 View 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 View 在那里，但如果它们的宽度/高度为零(尤其是当您裁剪到边界时)，您将看不到它。