动画UISlider顺利 [英] Animate UISlider smoothly

问题描述

我要对动画的例如UISlider 0.25〜0.75和背部。这应该显示什么是做用户。

i want to animate an UISlider for e.g. 0.25 to 0.75 and back. This should show the user what is to do.

我想这：

[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];
}

但那不是那么顺利......我可以用转换为这个？

but thats not so smooth... can i use transitions for this?

[Slider setValue:1 animated:YES];

是快速...

[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...

Just animates the second one...

推荐答案

您需要链动画通过将第二个动画第一完成块：

You need to chain the animations by putting the second animation in the completion block of the first:

-(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
        }];
    }];
}

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