在 for 循环中更改 CAShapeLayer 的路径无效

Question

我在for 循环中更改CAShapeLayer 的路径，但它只显示循环的最后结果。我知道，我可以用 CABasicAnimation 做到这一点，但我需要以这种方式改变路径。任何想法如何做到这一点？

UIBezierPath *path = [ShapeManager getCirclePathAppendedWithCirclePathWithRadius:radius
                                                                        andFrame:self.view.bounds];
self.layer.fillRule = kCAFillRuleEvenOdd;
self.layer.fillColor = [UIColor grayColor].CGColor;
self.layer.opacity = 0.5;
self.layer.path = path.CGPath;
[self.view.layer addSublayer:self.layer];
for (int i = 1; i < 100; ++i) {
    path = [ShapeManager getCirclePathAppendedWithCirclePathWithRadius:self.view.bounds.size.width-i
                                                              andFrame:self.view.bounds];
    self.layer.path = path.CGPath;
}

辅助方法

+ (UIBezierPath *)getCirclePathAppendedWithCirclePathWithRadius:(CGFloat)radius andFrame:(CGRect)frame {
    UIBezierPath *backgroundPath = [UIBezierPath bezierPathWithRect:frame];
    [backgroundPath appendPath:[self getCirclePathWithRadius:radius andFrame:frame]];
    return backgroundPath;
}

+ (UIBezierPath *)getCirclePathWithRadius:(CGFloat)radius andFrame:(CGRect)frame {
    CGRect rect = frame;
    UIBezierPath *circlePath;
    circlePath = [UIBezierPath bezierPathWithArcCenter:(CGPoint){rect.size.width/2, rect.size.height/2} radius:radius startAngle:0 endAngle:M_PI*2 clockwise:YES];
    return circlePath;
}

Answer 1

使用 CABasicAnimation 是对的。

1. 删除您的for 循环，它不会完成这项工作。
2. 为path 键添加CABasicAnimation，并在其间插入值。这段代码只能在viewDidLoad 方法中调用一次：

UIBezierPath *fromPath = [self.class getCirclePathAppendedWithCirclePathWithRadius:self.view.bounds.size.width andFrame:self.view.bounds];
UIBezierPath *toPath = [self.class getCirclePathAppendedWithCirclePathWithRadius:self.view.bounds.size.width-99 andFrame:self.view.bounds];

CABasicAnimation * animation = [CABasicAnimation animationWithKeyPath:@"path"];
animation.fromValue = (id)fromPath.CGPath;
animation.toValue = (id)toPath.CGPath;
animation.duration = 1; 

[layer addAnimation:animation forKey:@"pathAnimation"];
layer.speed = 0;

更新：

1. 在最后一行中，您将 speed 值设置为 0，因为您要手动设置动画进度：

@property (nonatomic, assign) double progress;

- (void) setProgress: (double) progress {
    _progress = progress;        
    layer.timeOffset = (CFTimeInterval)progress; 
}

这假设动画持续时间为 1.0。否则需要设置

layer.timeOffset = (CFTimeInterval)(progress * totalDuration);

现在只需根据更新的值设置运动回调的进度。