带有 CustomView 的 MBProgressHUD：为什么我不能为我的自定义视图设置动画？

Question

这不知何故不起作用...为什么？如何在不从动画中制作 gif 的情况下实现旋转的自定义螺旋桨？

-(UIView *)propTest
{
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 37, 37)];

    UIImageView *movablePropeller = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 37 , 37)];

    movablePropeller.image = [UIImage imageNamed:@"MovablePropeller"];


    [view addSubview:movablePropeller];
    movablePropeller.center = view.center;

    CABasicAnimation *rotation;
    rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    rotation.fromValue = [NSNumber numberWithFloat:0.0f];
    rotation.toValue = [NSNumber numberWithFloat:(2 * M_PI)];
    rotation.cumulative = true;
    rotation.duration = 1.2f; // Speed
    rotation.repeatCount = INFINITY; // Repeat forever. Can be a finite number.

    [movablePropeller.layer addAnimation:rotation forKey:@"Spin"];

    return view;
}

-(void)presentMyHud
{
    MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView:self.view];
    [self.view addSubview:hud];
    hud.mode = MBProgressHUDModeCustomView;
    hud.customView = [self propTest];
    hud.detailsLabelText = @"Getting data";
    [hud show:YES];
}

但我的螺旋桨保持静止......

Answer 1

如果螺旋桨没有旋转，如果您没有立即将此 view 添加到视图层次结构中，可能会发生这种情况。通常，将视图添加到视图层次结构中是谨慎的在你addAnimation。

- (UIView *)addPropellerToView:(UIView *)view {
    UIView *containerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 37, 37)];

    // make sure to add it to the view hierarchy

    [view addSubview:containerView];

    // if you want to center it, set its `center` to be in the middle of the `bounds` ... don't use `center`

    containerView.center = CGPointMake(view.bounds.origin.x + view.bounds.size.width / 2, view.bounds.origin.y + view.bounds.size.height / 2);

    // I'd just use the `bounds` of the container view; reducing the risk that we get its coordinates wrong

    UIImageView *movablePropeller = [[UIImageView alloc] initWithFrame:containerView.bounds];

    movablePropeller.image = [UIImage imageNamed:@"MovablePropeller"];
    movablePropeller.contentMode = UIViewContentModeScaleAspectFill;

    [containerView addSubview:movablePropeller];

    // never set the center of a view to the center of its super view ... those are two different coordinate systems.
    // in this case, this line isn't needed at all, so I'll remove it.
    //
    //     movablePropeller.center = containerView.center;

    CABasicAnimation *rotation;
    rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    rotation.fromValue = @(0);
    rotation.toValue = @(2 * M_PI);
    rotation.cumulative = true;
    rotation.duration = 1.2f;
    rotation.repeatCount = INFINITY;

    [movablePropeller.layer addAnimation:rotation forKey:@"Spin"];

    return containerView;
}

产量：

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一些不相关的观察：

• 如果要将视图 A 置于视图 B 的中间，请将视图 A 的 center 设置为 B 的 bounds 的中点，而不是 B 的 center。例如，你永远不想做：

  A.center = B.center;
  

  你想要的是：

  A.center = CGPointMake(B.bounds.origin.x + B.bounds.size.width / 2, B.bounds.origin.y + B.bounds.size.height / 2);
  

  我知道它看起来应该是同一件事，但事实并非如此。 A 的center 和frame 一样是在B 的坐标系中定义的。但是B 的center 是在其父视图的坐标系中定义的，可能完全不同。有时你不会注意到差异（特别是如果 B 的 origin 是 {0, 0}），但这表明对不同坐标系的误解，如果 B 不在 {0, 0}，那么一切都会出错。

• 您可以使用NSNumber 文字，将[NSNumber numberWithFloat:0.0f] 替换为@(0)。

• 你真的不需要那个容器视图，所以你可以简化例程，如下所示。

  - (UIView *)addPropellerTo:(UIView *)view {
      UIImageView *movablePropeller = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 37, 37)];
      movablePropeller.image = [UIImage imageNamed:@"MovablePropeller"];
      movablePropeller.contentMode = UIViewContentModeScaleAspectFill;
      [view addSubview:movablePropeller];
      movablePropeller.center = CGPointMake(view.bounds.origin.x + view.bounds.size.width / 2, view.bounds.origin.y + view.bounds.size.height / 2);
  
      CABasicAnimation *rotation;
      rotation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
      rotation.fromValue = @(0);
      rotation.toValue = @(2 * M_PI);
      rotation.cumulative = true;
      rotation.duration = 1.2f;
      rotation.repeatCount = INFINITY;
  
      [movablePropeller.layer addAnimation:rotation forKey:@"Spin"];
  
      return movablePropeller;
  }