ios - 平滑地为 UISlider 设置动画

Question

我想为例如 0.25 到 0.75 并返回的 UISlider 设置动画。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];

是快...

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

只是动画第二个...

Answer 1

您需要通过将第二个动画放在第一个动画的完成块中来链接动画：

-(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
        }];
    }];
}

Answer 2

用于 rdelmar 的Swift 2.2 版本

@IBOutlet weak var slider: UISlider!

func animateSlider(sender: AnyObject){
    UIView.animateWithDuration(2, animations:  {() in
        self.slider.setValue(0.75, animated: true)
        }, completion:{(Bool)  in
            UIView.animateWithDuration(2, animations: {() in
                self.slider.setValue(0.25, animated: true)
            })
    })
}

并调用函数在参数中传递 UISlider

animateSlider(self.slider)