ios - 流畅地动画化 UISlider

Question

我想为 UISlider 制作动画，例如0.25 到 0.75 并返回。这应该向用户展示要做什么。

我试过这个:

[self incrementCounter:[NSNumber numberWithInt:0]];


-(void) incrementCounter:(NSNumber *)i {
    [Slider setValue:[i floatValue]/1000];
    [self performSelector:@selector(incrementCounter:) withObject:[NSNumber numberWithInt:i.intValue+1] afterDelay:0.001];
}

但这不是那么顺利...我可以为此使用过渡吗？

[Slider setValue:1 animated:YES];

要快...

[UIView animateWithDuration:2.0
                 animations:^{
                     [Slider setValue:0.2];
                 }];
[UIView animateWithDuration:2.0
                 animations:^{
                     [Slider setValue:0.5];
                 }];

只为第二个制作动画......

Answer 1

您需要通过将第二个动画放在第一个动画的完成 block 中来链接动画:

-(IBAction)animateSlider:(id)sender {

    [UIView animateWithDuration:2 animations:^{
        [self.slider setValue:.75];
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:2 animations:^{
            [self.slider setValue:0.25];//or `[self.slider setValue:(.75)-(.5*finished)];` if you want to be safe
        }];
    }];
}