CAShapeLayer 动画问题 iOS7

Question

我一直在为 iOS7 的动画效果而苦苦挣扎（8、9 它工作正常）涉及将圆角矩形收缩成圆形。才能达到这样的效果。

但是当我尝试在 iOS7 上收缩圆圈时出现了一些失真。

我的视图控制器非常简单

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    CAShapeLayer *layer = [CAShapeLayer layer];
    layer.fillColor = [UIColor blackColor].CGColor;
    layer.frame = CGRectMake(100, 100, 100, 100);
    layer.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 100, 50) cornerRadius:25].CGPath;
    self.myLayer = layer;
    [self.view.layer addSublayer:layer];

}


- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"path"];
    animation.values = @[
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 100, 50) cornerRadius:25].CGPath,
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(5, 0, 90, 50) cornerRadius:25].CGPath,
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(10, 0, 80, 50) cornerRadius:25].CGPath,
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(15, 0, 70, 50) cornerRadius:25].CGPath,
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, 0, 60, 50) cornerRadius:25].CGPath,
                         (id)[UIBezierPath bezierPathWithRoundedRect:CGRectMake(25, 0, 50, 50) cornerRadius:25].CGPath,
                         ];

    animation.keyTimes = @[@(0),
                           @(0.18),
                           @(0.36),
                           @(0.54),
                           @(0.72),
                           @(1),
                           ];

    animation.duration = 10;
    animation.fillMode = kCAFillModeForwards;
    [self.myLayer addAnimation:animation forKey:nil];
    self.myLayer.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(25, 0, 50, 50) cornerRadius:25].CGPath;
}

Answer 1

这似乎是 iOS 7 的错误。检查这个 link:

http://www.paintcodeapp.com/blogpost/code-for-ios-7-rounded-rectangles

post 底部有一个分类方法解决了这个问题。我用你的代码测试了它，它似乎有效！我不得不做一个小改动，那就是替换

CGFloat limitedRadius = MIN(radius, limit);

与

CGFloat limitedRadius = radius;

这使得角半径变得足够大以创建一个圆。可能值得研究为什么角半径首先受到限制，但我会把它留给你:)

CAShapeLayer 动画问题 iOS7

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