scrollView完成滚动是走的代理

当人为滚动时(屏幕滑动的方式)走

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

方法;
当用[scrollView setContentOffset:CGPointMake(WIDTH, 0) animated:YES]方法滚动时走

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView

方法;