创建自定义动画属性 [英] Create a custom animatable property

问题描述

在 UIView 上，您可以更改backgroundColour动画。在 UISlideView 上，您可以更改动画值。

您可以将自定义属性添加到您自己的 UIView 子类，以便它可以设置动画？

如果我有一个 CGPath 在我的 UIView 中，然后我可以通过更改路径绘制的百分比来设置它的绘图。

我可以将该动画封装到子类中。

ie我有一个 UIView ，带有 CGPath ，可以创建一个圆圈。

如果圆圈不存在则代表0％。如果圆圈已满，则表示100％。我可以通过改变路径绘制的百分比来绘制任何值。我还可以通过动画 CGPath 的百分比并重新绘制路径来动画更改（在UIView子类中）。

<我可以在 UIView 上设置一些属性（即百分比），这样我就可以将更改保持在 UIView animateWithDuration 阻止并为路径百分比的变化设置动画？

我希望我已经解释了我想做的事情。

基本上，我想做的就是... ...

  [UIView animateWithDuration：1.0 
动画：^ {
 myCircleView.percentage = 0.7; 
} 
完成：nil]; 
  

以及给定百分比设置的圆形路径。

解决方案

如果您扩展CALayer并实现自定义

   - （void） drawInContext：（CGContextRef）context 
  

你可以通过覆盖 needsDisplayForKey来创建一个可动画的属性（在您的自定义CALayer类中），如下所示：

  +（BOOL）needsDisplayForKey：（NSString * ）key {
 if（[key isEqualToString：@percentage]）{
 return YES; 
} 
 return [super needsDisplayForKey：key]; 
} 
  

当然，你还需要一个 @ property 名为百分比。从现在开始，您可以使用核心动画为百分比属性设置动画。我也没有使用 [UIView animateWithDuration ...] 调用来检查它是否有效。它可能会奏效。但这对我有用：

  CABasicAnimation * animation = [CABasicAnimation animationWithKeyPath：@percentage]; 
 animation.duration = 1.0; 
 animation.fromValue = [NSNumber numberWithDouble：0]; 
 animation.toValue = [NSNumber numberWithDouble：100]; 
 
 [myCustomLayer addAnimation：animation forKey：@animatePercentage]; 
  

哦，并使用 yourCustomLayer myCircleView ，执行此操作：

  [myCircleView.layer addSublayer：myCustomLayer]; 
  

On UIView you can change the backgroundColour animated. And on a UISlideView you can change the value animated.

Can you add a custom property to your own UIView subclass so that it can be animated?

If I have a CGPath within my UIView then I can animate the drawing of it by changing the percentage drawn of the path.

Can I encapsulate that animation into the subclass.

i.e. I have a UIView with a CGPath that creates a circle.

If the circle is not there it represents 0%. If the circle is full it represents 100%. I can draw any value by changing the percentage drawn of the path. I can also animate the change (within the UIView subclass) by animating the percentage of the CGPath and redrawing the path.

Can I set some property (i.e. percentage) on the UIView so that I can stick the change into a UIView animateWithDuration block and it animate the change of the percentage of the path?

I hope I have explained what I would like to do well.

Essentially, all I want to do is something like...

[UIView animateWithDuration:1.0
 animations:^{
     myCircleView.percentage = 0.7;
 }
 completion:nil];

and the circle path animate to the given percentage.

解决方案

If you extend CALayer and implement your custom

- (void) drawInContext:(CGContextRef) context

You can make an animatable property by overriding needsDisplayForKey (in your custom CALayer class) like this:

+ (BOOL) needsDisplayForKey:(NSString *) key {
    if ([key isEqualToString:@"percentage"]) {
        return YES;
    }
    return [super needsDisplayForKey:key];
}

Of course, you also need to have a @property called percentage. From now on you can animate the percentage property using core animation. I did not check whether it works using the [UIView animateWithDuration...] call as well. It might work. But this worked for me:

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"percentage"];
animation.duration = 1.0;
animation.fromValue = [NSNumber numberWithDouble:0];
animation.toValue = [NSNumber numberWithDouble:100];

[myCustomLayer addAnimation:animation forKey:@"animatePercentage"];

Oh and to use yourCustomLayer with myCircleView, do this:

[myCircleView.layer addSublayer:myCustomLayer];

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