Question

我有UIView名为activityView，其中包含两个子视图activityIndicator和cancelOperationsButton。这些视图嵌入在XIB中，并连接到我的视图控制器。

我有两种处理激活（显示）和停用（隐藏）这两个子视图的方法：

- (void) enableActivityIndicator {
    [activityIndicator startAnimating];
    [cancelOperationsButton setHidden:NO];
}

- (void) disableActivityIndicator {
    [activityIndicator stopAnimating];
    [cancelOperationsButton setHidden:YES];
}

这两种方法本身就可以正常工作。

为了给这点做一些改进，我想添加一个动画来淡化这些子视图：

- (void) enableActivityIndicator {
    [activityIndicator startAnimating];
    [cancelOperationsButton setHidden:NO];

    [UIView beginAnimations:@"fadeIn" context:nil];
    [UIView setAnimationDelay:0.0f];
    [UIView setAnimationDuration:1.0f];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
    activityView.alpha = 1.0f;
    [UIView commitAnimations];
}

- (void) disableActivityIndicator {
    [UIView beginAnimations:@"fadeOut" context:nil];
    [UIView setAnimationDelay:0.0f];
    [UIView setAnimationDuration:1.0f];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    activityView.alpha = 0.0f;
    [UIView commitAnimations];

    [activityIndicator stopAnimating];
    [cancelOperationsButton setHidden:YES];
}

但是动画无法正常工作 - 只有父视图的alpha属性对透明度产生影响时，子视图才会显示或消失。

我应该如何编写这些方法来获得我追求的淡入淡出效果？

修改

这是一种完美运作的安排：

- (void) enableActivityIndicator {
    activityView.alpha = 0.0f;
    [activityIndicator startAnimating];
    [cancelOperationsButton setHidden:NO];

    [UIView beginAnimations:@"fadeIn" context:nil];
    [UIView setAnimationDelay:0.0f];
    [UIView setAnimationDuration:0.2f];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
    activityView.alpha = 1.0f;
    [UIView commitAnimations];
}

- (void) disableActivityIndicator {
    [UIView beginAnimations:@"fadeOut" context:nil];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(disableActivityIndicatorComplete)];
    [UIView setAnimationDelay:0.0f];
    [UIView setAnimationDuration:0.2f];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    activityView.alpha = 0.0f;
    [UIView commitAnimations];
}

- (void) disableActivityIndicatorComplete {
    [activityIndicator stopAnimating];
    [cancelOperationsButton setHidden:YES];
}

Answer 1

在启用时，将视图设置为在动画化为不透明之前清除。

- (void) enableActivityIndicator {
    ...
    activityView.alpha = 0.0f;
    [cancelOperationsButton setHidden:NO];
    ...

在禁用时，请勿在动画完成后隐藏视图。

- (void) disableActivityIndicator {
    ...
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(hideComplete)];
    ...

- (void) hideComplete {
    [activityIndicator stopAnimating];
    [cancelOperationsButton setHidden:YES];
}

我的核心动画块不像我期望的那样工作

1 个答案: