从下至上对UIButton背景颜色进行动画处理，目标C [英] Animate UIButton Background color from bottom up, Objective C

问题描述

我有一个按钮，希望对背景颜色进行动画处理，好像它是从底部填充到顶部一样。

I have a button which I would like to animate the background color as if it is filling from the bottom to the top.

现在我只是在更改动画的颜色

Right now I'm just changing the color with animation

ie

[UIView animateWithDuration:2.0 animations:^{
    button.layer.backgroundColor = [UIColor redColor].CGColor;
} completion:NULL];

效果很好，但我希望动画从下往上填充

This works just fine but I'd love the animation to fill from the bottom up like it is filling up with liquid.

编辑：不确定是否有区别，但按钮是圆形的

not sure if it makes a difference but the button is round

推荐答案

尝试一下。这里的btn是按钮的出口，而v是我们将添加到按钮以进行动画处理的视图。

Try this. Here btn is the outlet to your button and v is the view we will be adding to your button for animation purpose.

UIView *v = [[UIView alloc] initWithFrame:CGRectMake(0, [self btn].frame.size.height,
                                                     [self btn].frame.size.width, [self btn].frame.size.height)];
[v setBackgroundColor:[UIColor purpleColor]];
v.userInteractionEnabled = NO;
v.exclusiveTouch = NO;
[[self btn] addSubview:v];

[UIView animateWithDuration:0.45 animations:^{

    CGRect currentRect = v.frame;
    currentRect.origin.y = 0;
    [v setAlpha:1];
    [v setFrame:currentRect];
    [[self btn] sendSubviewToBack:v];
}];

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