CALayer CABasicAnimation链接

Question

我使用以下代码为CALayer的opacity属性设置动画:

在方法中创建动画:

+ (CABasicAnimation *)fadeIn:(float)begin duration:(float)duration remove:(BOOL)remove{

    CABasicAnimation *fadeAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
    fadeAnimation.fromValue = [NSNumber numberWithFloat:0.0];
    fadeAnimation.toValue = [NSNumber numberWithFloat:1.0];
    fadeAnimation.additive = NO;
    fadeAnimation.removedOnCompletion = remove;
    fadeAnimation.beginTime = begin;
    fadeAnimation.duration = duration;
    fadeAnimation.fillMode = kCAFillModeBoth;

    return fadeAnimation;
}

将动画添加到图层:

[overlayLayer addAnimation:[VideoComposerHelpers fadeIn:1.0 duration:0.5 remove:NO] forKey:nil];

这是完美的.但是,现在我想在第一个动画完成后立即向同一个图层添加另一个动画.

[overlayLayer addAnimation:[VideoComposerHelpers fadeOut:1.5 duration:0.5 remove:NO] forKey:nil]; // fadeOut is a method similar to fadeIn

应该发生的是,图层以0.5的持续时间淡入,之后,它会以0.5的持续时间淡出.但这似乎不起作用.是因为第二个动画的起点与第一个动画的终点相同吗？

Answer 1

你应该使用这样的CAAnimationGroup东西:

CABasicAnimation *fadeIn  = [VideoComposerHelpers fadeIn:1.0 duration:0.5 remove:NO];
CABasicAnimation *fadeOut = [VideoComposerHelpers fadeOut:1.5 duration:0.5 remove:NO];

CAAnimationGroup *group = [CAAnimationGroup animation];
group.fillMode = kCAFillModeForwards;
group.removedOnCompletion = NO;
[group setAnimations:[NSArray arrayWithObjects:fadeIn, fadeOut, nil]];
group.duration = 2;
[overlayLayer addAnimation:group forKey:@"savingAnimation"];

此外,我不确定我是否得到正确的值,包括动画的开始,结束,持续时间(你应该检查它们):)).