带有CustomView的MBProgressHUD：为什么不能设置自定义视图的动画？

Question

这不起作用...为什么？如何在不制作动画gif的情况下实现旋转自定义螺旋桨？

-(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];
}

但是我的螺旋桨保持静止...

Answer 1

如果螺旋桨未旋转，则可能是由于您没有立即将view添加到视图层次结构中。通常，谨慎地将视图添加到视图层次结构中[您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;
}

一些不相关的观察结果：

• 如果要将视图A在视图B的中间居中，请将视图A的center设置为与B的bounds的中点协调，而不是B的center。例如，您永远不想做：

  A.center = B.center;

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

  我知道看起来应该是同一回事，但事实并非如此。在B的坐标系中定义了A的center，与frame类似。但是在B的坐标系
  其上级视图
  中定义了B的center，这可能是完全不同的。有时您不会注意到差异（特别是如果B的origin为{0, 0}），但是这暗示了对不同坐标系的误解，并且如果B不在{0, 0}，那么一切都会出错。] >

• 您可以使用NSNumber文字，用[NSNumber numberWithFloat:0.0f]替换@(0)。
• 您确实不需要该容器视图，因此可以简化例程，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;
}