UIScrollViewDelegate 方法调用

/** 设置缩放的View, 初始化完之后调用此方法告诉scrollView 谁可以缩放操作, 然后进行布局 */
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
    print("viewForZoomingInScrollView")
    
    return imageView
}

/** 缩放进行中调用 */
func scrollViewDidZoom(scrollView: UIScrollView) {
    print("scrollViewDidZoom")
    
    centerScrollViewContents()
}

/** 缩放开始调用 */
func scrollViewWillBeginZooming(scrollView: UIScrollView, withView view: UIView?)  {
    print("scrollViewWillBeginZooming")
}

/** 缩放结束调用 */
func scrollViewDidEndZooming(scrollView: UIScrollView, withView view: UIView?, atScale scale: CGFloat) {
    print("scrollViewDidEndZooming")
}

/** 改变 offset调用: 缩放, 拖拽都会改变offset */
func scrollViewDidScroll(scrollView: UIScrollView) {
    print(scrollView.contentOffset)
    print("scrollViewDidScroll")
}

/** 开始拖拽调用 */
func scrollViewWillBeginDragging(scrollView: UIScrollView){
    print("scrollViewWillBeginDragging")
}

/** 即将结束拖拽调用 */
func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>){
    print("scrollViewWillEndDragging")
}

/** 结束拖拽调用 */
func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool){
    print("scrollViewDidEndDragging")
}

func scrollViewWillBeginDecelerating(scrollView: UIScrollView){
    print("scrollViewWillBeginDecelerating")
}

/** 拖拽动画即将停止调用 */
func scrollViewDidEndDecelerating(scrollView: UIScrollView){
    print("scrollViewDidEndDecelerating")
}

/** 当用代码设置scrollRectToVisible/ setContentOffset 时候调用 (注意 后面的animated 一定要传true, 否则不会触发)*/
func scrollViewDidEndScrollingAnimation(scrollView: UIScrollView){
    print("scrollViewDidEndScrollingAnimation")
}

/** 当点击(collectionView/ tableView y值滚动到某个位置)状态栏时候调用 */
func scrollViewShouldScrollToTop(scrollView: UIScrollView) -> Bool{
    print("scrollViewShouldScrollToTop")
    return true
}

/** 点击状态栏回到顶部调用 */
func scrollViewDidScrollToTop(scrollView: UIScrollView)  {
    print("scrollViewDidScrollToTop")
}