ios - 如何检测 UIScrollView 何时在 Swift 中完成滚动

Question

众所周知，Ashley Smart ( How to detect when a UIScrollView has finished scrolling ) 在 Obj-C 中提出了解决此问题的出色解决方案。

-(void)scrollViewDidScroll:(UIScrollView *)sender 
{   
[NSObject cancelPreviousPerformRequestsWithTarget:self];
    //ensure that the end of scroll is fired.
    [self performSelector:@selector(scrollViewDidEndScrollingAnimation:) withObject:nil afterDelay:0.3]; 

...
}

-(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{
    [NSObject cancelPreviousPerformRequestsWithTarget:self];
...
}

但是，我需要一个 Swift 中的解决方案。

看来，由 Matt ( dispatch_after - GCD in swift?) 贡献的优秀延迟函数可能会有所帮助。

func delay(delay:Double, closure:()->()) {
    dispatch_after(
        dispatch_time(
            DISPATCH_TIME_NOW,
            Int64(delay * Double(NSEC_PER_SEC))
        ),
        dispatch_get_main_queue(), closure)
}

并实现为...

delay(0.4) {
    // do stuff
}

但我还没有把它放在一起。有什么帮助吗？

Answer 1

委托(delegate)方法告诉你何时完成

func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
    self.stoppedScrolling()
}

func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
    if !decelerate {
        self.stoppedScrolling()
    }
}

func stoppedScrolling() {
    println("Scroll finished")
}