如何判斷ScrollView滑動方向

1/判斷滾動視圖左右滾動

   {
　   CGFloat startContentOffsetX;//滾動開始的坐標
    CGFloat willEndContentOffsetX; //滾動即將停止的坐標
    CGFloat endContentOffsetX;//滾動結束的坐標

　}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    myPC.currentPage = scrollView.contentOffset.x / scrollView.frame.size.width;
    currNum = (int)myPC.currentPage;
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
     startContentOffsetX = scrollView.contentOffset.x;
    [self stopTimer];
}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{    //將要停止前的坐標
    willEndContentOffsetX = scrollView.contentOffset.x;
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    
    endContentOffsetX = scrollView.contentOffset.x;
    
    if (endContentOffsetX < willEndContentOffsetX && willEndContentOffsetX < startContentOffsetX) { //畫面從右往左移動，前一頁
        isNext = NO;
    } else if (endContentOffsetX > willEndContentOffsetX && willEndContentOffsetX > startContentOffsetX) {//畫面從左往右移動，后一頁
        isNext = YES;
    }
    [self starTimer];
}

2/判斷上下滾動視圖上下滾動

float lastContentOffset;
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    lastContentOffset = scrollView.contentOffset.y; 
}
 
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView{
    if (lastContentOffset < scrollView.contentOffset.y) {
        NSLog(@"向上滾動");
    }else{
        NSLog(@"向下滾動");
    }
}