Question

如何判断UIScrollView滑动方向

Answer 1

工作需要，需要实现UIScrollView左右拖动加载，

首先设置pageEnable=YES；

然后通过Delegate实现相关方法。

//将要开始拖拽，手指已经放在view上并准备拖动的那一刻

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{ //拖动前的起始坐标

startContentOffsetX = scrollView.contentOffset.x;

}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{ //将要停止前的坐标

willEndContentOffsetX = scrollView.contentOffset.x;

}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

endContentOffsetX = scrollView.contentOffset.x;

if (endContentOffsetX < willEndContentOffsetX && willEndContentOffsetX < startContentOffsetX) { //画面从右往左移动，前一页

} else if (endContentOffsetX > willEndContentOffsetX && willEndContentOffsetX > startContentOffsetX) {//画面从左往右移动，后一页

}

}

如上可判断ScrollView是左移了还是右移了

Answer 2

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{ //Selected index's color changed. static float newx = 0; static float oldIx = 0; newx= scrollView.contentOffset.x ; if (newx != oldx ) { //Left-YES,Right-NO if (newx > oldx) { self.scrollLeftOrRight = NO; }else if(newIndex < oldIndex){ self.scrollLeftOrRight = YES; } oldx = newx; } }