简单的 UIView 动画链不起作用

Question

我正在尝试将 UIImageView 滑入 UIView 中，并同时将其淡入。然后我希望它淡出并滑出。 下面的代码应该执行此操作，但事实并非如此。 相反，leftArrow 视图在滑入时处于完整的 Alpha 状态。因此第一个动画会跳过 Alpha 淡入。然后第二个动画只是淡出它，它不会移动 leftArrow 视图。我尝试了很多变体（使用边界而不是框架，在类方法中执行动画（而不是实例方法），并且我无法确定为什么视图似乎任意选择一件事而不是另一件事，或两者兼而有之。 也许我只是需要新鲜的眼光。 TIA， 迈克

- (void) flashHorizontalArrowsForView: (UIView *)view {
DebugLog(@" flashHorizontalArrows");


    float duration = 1.5f;

    // create the views
    UIImageView *leftArrow = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"leftCouponDetailArrow.png"]];
    leftArrow.frame = CGRectMake(0 -leftArrow.image.size.width, 
                                 HORIZONTAL_ARROW_START_Y, 
                                 leftArrow.image.size.width, 
                                 leftArrow.image.size.height);

    [view addSubview:leftArrow];
    leftArrow.alpha =  0.0f;

    // animate them in...
    [UIView beginAnimations:@"foo" context:leftArrow];
    [UIView setAnimationDelay:    0.0f ];       // in seconds   
    [UIView setAnimationDuration: duration ];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
    [UIView setAnimationDidStopSelector:@selector(animationReallyDidStop:finished:context:)];
    [UIView setAnimationDelegate:self];

    leftArrow.alpha = 1.0f;

    CGRect LFrame = leftArrow.frame;
    LFrame.origin.x += LFrame.size.width;  // move it in from the left.
    leftArrow.frame = LFrame;

    [UIView commitAnimations];

    // and animate them out
    // delay enough for the first one to finish  
    [UIView beginAnimations:@"bar" context:leftArrow];
    [UIView setAnimationDelay:    duration+0.05 ];       // in seconds  
    [UIView setAnimationDuration: duration ];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    [UIView setAnimationDidStopSelector:@selector(animationReallyDidStop:finished:context:)];
    [UIView setAnimationDelegate:self];
    leftArrow.alpha  = 0.0f;

    CGRect LLFrame = leftArrow.bounds;
    LLFrame.origin.x -= LLFrame.size.width;  // move it off to the left.
    leftArrow.bounds = LLFrame;

    [UIView commitAnimations];

}

Answer 1

解决方案很简单 - 当第一个动画完成时，让它调用另一个方法，例如horizo​​ntal2，并在horizo​​ntal2中执行animate_them_out部分。

- (void) flashHorizontalArrowsForView: (UIView *)view{
DebugLog(@" flashHorizontalArrows");
self.theView = view;

float duration = 1.5f;

// create the views
UIImageView *left = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"leftCouponDetailArrow.png"]];
self.leftArrow = left;
[left release];
leftArrow.tag = LEFT_ARROW_TAG;
leftArrow.frame = CGRectMake(0 -leftArrow.image.size.width, 
                             HORIZONTAL_ARROW_START_Y, 
                             leftArrow.image.size.width, 
                             leftArrow.image.size.height);

[theView addSubview:leftArrow];
leftArrow.alpha =  0.0f;

UIImageView *right = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"rightCouponDetailArrow.png"]];
self.rightArrow = right;
[right release];
rightArrow.tag = RIGHT_ARROW_TAG;
rightArrow.frame = CGRectMake(view.frame.size.width, // -leftArrow.image.size.width, 
                             HORIZONTAL_ARROW_START_Y, 
                             leftArrow.image.size.width, 
                             leftArrow.image.size.height);

[theView addSubview:rightArrow];
rightArrow.alpha =  0.0f;

// --------------------------------------------
// animate them in...
[UIView beginAnimations:@"foo" context:nil];
[UIView setAnimationDelay:    0.0f ];       // in seconds   
[UIView setAnimationDuration: duration ];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDidStopSelector:@selector(horizontalPart2)];
[UIView setAnimationDelegate:self];

leftArrow.alpha  = 1.0f;
rightArrow.alpha = 1.0f;

CGRect LFrame = leftArrow.frame;
LFrame.origin.x += LFrame.size.width;  // move it in from the left.
leftArrow.frame = LFrame;

CGRect RFrame = rightArrow.frame;
RFrame.origin.x -= RFrame.size.width;  // move it in from the right.
rightArrow.frame = RFrame;
[UIView commitAnimations];

}

 - (void) horizontalPart2 {

// --------------------------------------------
// and animate them out
// delay enough for the first one to finish  
[UIView beginAnimations:@"bar" context:nil];
[UIView setAnimationDelay:    1.0f ];       // in seconds   
[UIView setAnimationDuration: 3.0f ];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
[UIView setAnimationDidStopSelector:@selector(horizontalAnimationDidStop:finished:context:)];
[UIView setAnimationDelegate:self];


CGRect LLFrame = leftArrow.frame;
LLFrame.origin.x -= LLFrame.size.width;  // move it off to the left.  // THIS IS NOT HAPPENING.
leftArrow.frame = LLFrame;

CGRect RFrame = rightArrow.frame;
RFrame.origin.x += RFrame.size.width;
rightArrow.frame = RFrame;

leftArrow.alpha   = 0.0f;
rightArrow.alpha  = 0.0f;

[UIView commitAnimations]; 

}