Core Animation：正确设置动画属性

我目前正在尝试使用Core Animation和图层来创建条形图视图。为了让它变得更凉爽，我试图让每束光芒一个接一个地弹出来。为了方便起见，我垂直翻转了视图的坐标系。Core Animation：正确设置动画属性

下面的代码：

- (id)initWithFrame:(CGRect)frame 
{ 
    self = [super initWithFrame:frame]; 
    if (self) { 
     self.transform = CGAffineTransformMakeScale(1, -1); 
     self.values = @[@12.5f, @4.25f, @23.0f, @3.0f, @17.9f, @7.0f, @15.1f]; 
    } 
    return self; 
} 

- (void)didMoveToSuperview 
{ 
    self.backgroundColor = [UIColor whiteColor]; 
    self.beamContainer = [CALayer layer]; 
    CGRect frame = CGRectInset(self.bounds, 20, 20); 
    self.beamContainer.frame = frame; 
    self.beamContainer.backgroundColor = [UIColor colorWithWhite:0.98 alpha:1].CGColor; 
    float maxValue = [[self.values valueForKeyPath:@"@max.floatValue"] floatValue]; 
    for (int i = 0; i < self.values.count; i++) { 
     CALayer *beam = [CALayer layer]; 
     CGFloat beamHeight = ([self.values[i] floatValue] * frame.size.height)/maxValue; 

     beam.backgroundColor = [UIColor colorWithRed:0.5 green:0.6 blue:1 alpha:1].CGColor; 
     beam.anchorPoint = CGPointMake(0, 0); 
     beam.position = CGPointMake(frame.size.width * ((float)i/(float)self.values.count), 0); 
     CGRect endBounds = CGRectMake(0, 0, frame.size.width /(float)self.values.count, beamHeight); 
     CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"bounds"]; 
     animation.fromValue = [NSValue valueWithCGRect:CGRectMake(0, 0, frame.size.width /(float)self.values.count, 5)]; 
     animation.toValue = [NSValue valueWithCGRect:endBounds]; 
     animation.duration = .5; 
     animation.beginTime = CACurrentMediaTime() + ((float)i * 0.1); 
     [beam addAnimation:animation forKey:@"beamAnimation"]; 

     [self.beamContainer addSublayer:beam]; 
     beam.bounds = endBounds; 
    } 
    [self.layer addSublayer:self.beamContainer]; 
}

这个工程就像一个魅力，唯一的问题是，如果我不写beam.bounds = endBounds;光束将迅速跳回它的老边界后的动画完成。但是当我这样做时，甚至在动画有开始之前以及每个动画的延迟期间，它都将使用endBounds。

如何使光束从边界A移动到B并粘到B上end？

来源

2013-07-17 Dario

看看CATransaction（http://developer.apple.com/library/ios/ipad/#documentation/GraphicsImaging/Reference/CATransaction_class/Introduction/Introduction.html），也许它会更好地满足您的需求。另外，看到这个职位：http://oleb.net/blog/2012/11/prevent-caanimation-snap-back/ – architectpianist

你使用自动布局？ – rdelmar

你可以尝试像以下：

// Save the original value 
CGFloat originalY = layer.position.y; 

// Change the model value (this is not animated yet) 
layer.position = CGPointMake(layer.position.x, 300.0); 

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position.y"]; 

// Now specify the fromValue for the animation because 
// the current model value is already the correct toValue 
animation.fromValue = @(originalY); 
animation.duration = 1.0; 

// Use the name of the animated property as key 
// to override the implicit animation 
[layer addAnimation:animation forKey:@"position"];

虽然它是不适合你正在尝试条形图动画完全匹配，你可以很可能会得到从上面的例子中的模式。 You can read more about it here.它帮助我解决了前几天发生的类似问题。

来源

2013-08-27 01:45:44

Core Animation：正确设置动画属性

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