动画 CALayer 边框变化

Question

我以这种方式将 border 宽度和颜色设置为 UIView 子类：

- (void) setViewBorder
{
    self.layer.borderColor = [UIColor greenColor].CGColor;
    self.layer.borderWidth = 3.0f;
}

我的问题是：如何制作动画？谢谢。

Answer 1

如果你只想淡入边框，你也可以这样做：

UIView.transition(with: self, duration: 0.3, options: .transitionCrossDissolve, animations: {

        self.layer.borderColor = UIColor.green.cgColor
        self.layer.borderWidth = 3

}, completion: nil)

Answer 2

这是@David 答案的快速解决方案：

let colorAnimation = CABasicAnimation(keyPath: "borderColor")
colorAnimation.fromValue = UIColor.red.cgColor
colorAnimation.toValue = UIColor.blue.cgColor
view.layer.borderColor = UIColor.blue.cgColor

let widthAnimation = CABasicAnimation(keyPath: "borderWidth")
widthAnimation.fromValue = 2
widthAnimation.toValue = 4
widthAnimation.duration = 4
view.layer.borderWidth = 4

let bothAnimations = CAAnimationGroup()
bothAnimations.duration = 0.5
bothAnimations.animations = [colorAnimation, widthAnimation]
bothAnimations.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)

view.layer.add(bothAnimations, forKey: "color and width")

Answer 3

borderColor 和 borderWidth 都是动画属性，但由于您是在 UIView 动画块之外的视图子类中执行此操作，因此会禁用隐式动画（当您更改值时自动发生的动画）。

如果您想为这些属性设置动画，则可以使用CABasicAnimation 进行显式动画。由于您在同一层上为两个属性设置动画，因此您可以将它们都添加到动画组中，并且只配置一次持续时间、时间等。请注意，显式动画是纯视觉的，添加它们时模型值（实际属性）不会改变。这就是为什么您既要配置动画又要设置模型值的原因。

CABasicAnimation *color = [CABasicAnimation animationWithKeyPath:@"borderColor"];
// animate from red to blue border ...
color.fromValue = (id)[UIColor redColor].CGColor;
color.toValue   = (id)[UIColor blueColor].CGColor;
// ... and change the model value
self.layer.borderColor = [UIColor blueColor].CGColor;

CABasicAnimation *width = [CABasicAnimation animationWithKeyPath:@"borderWidth"];
// animate from 2pt to 4pt wide border ...
width.fromValue = @2;
width.toValue   = @4;
// ... and change the model value
self.layer.borderWidth = 4;

CAAnimationGroup *both = [CAAnimationGroup animation];
// animate both as a group with the duration of 0.5 seconds
both.duration   = 0.5;
both.animations = @[color, width];
// optionally add other configuration (that applies to both animations)
both.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

[self.layer addAnimation:both forKey:@"color and width"];

如果您查看“设置插值值”部分下的the documentation for CABasicAnimation，您会发现不需要像我一样同时指定 toValue 和 fromValue，因此代码可以稍微短一些。但是，为了清晰和可读性（尤其是当您开始使用 Core Animation 时），更加明确可以帮助您（和您的同事）理解代码。

Answer 4

您可以创建关键帧动画并将其添加到您的视图中。

//Create animation
        CAKeyframeAnimation *colorsAnimation = [CAKeyframeAnimation animationWithKeyPath:@"borderColor"];
        colorsAnimation.values = [NSArray arrayWithObjects: (id)[UIColor greenColor].CGColor,
                                  (id)[UIColor yellowColor].CGColor, nil];
        colorsAnimation.keyTimes = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.25],[NSNumber numberWithFloat:1.0], nil];
        colorsAnimation.calculationMode = kCAAnimationLinear;
        colorsAnimation.removedOnCompletion = NO;
        colorsAnimation.fillMode = kCAFillModeForwards;
        colorsAnimation.duration = 3.0f;

    //Create animation
    CAKeyframeAnimation *sizeAnimation = [CAKeyframeAnimation animationWithKeyPath:@"borderWidth"];
    sizeAnimation.values = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],
                             [NSNumber numberWithFloat:5.0], nil];
    sizeAnimation.keyTimes = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],[NSNumber numberWithFloat:3.0], nil];
    sizeAnimation.calculationMode = kCAAnimationLinear;
    sizeAnimation.removedOnCompletion = NO;
    sizeAnimation.fillMode = kCAFillModeForwards;
    sizeAnimation.duration = 3.0f;

    //Add animation
    [yoursubview.layer   addAnimation:colorsAnimation forKey:nil];
    [yoursubview.layer   addAnimation:sizeAnimation forKey:nil];