我正在尝试在iOS 5中使用新的scrollViewWillEndDragging:withVelocity:targetContentOffset:UIScrollView委托调用,但我似乎无法正确地响应我。我正在更改targetContentOffset-> x值,但它永远不会最终被使用。我知道代码正在运行,因为它将在该函数中达到断点。我什至尝试将偏移量值设置为硬编码数字,这样我就知道它将在哪里结束但永远无法正常工作。
有人能正确使用它并使它起作用吗?为了使其正常工作,是否还必须执行其他任何委托调用?
这是我的代码,以防有人发现问题:
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
// goodOffsetX returns the contentOffset i want the scrollView to stop at
CGFloat goodOffsetX = [self _horizontalContentOffsetForTargetHorizontalContentOffset:(*targetContentOffset).x velocity:velocity.x];
NSLog( @" " );
NSLog( @"scrollViewWillEndDragging" );
NSLog( @" velocity: %f", velocity.x );
NSLog( @" currentX: %f", scrollView.contentOffset.x );
NSLog( @" uikit targetX: %f", (*targetContentOffset).x );
NSLog( @" pagedX: %f", goodOffsetX );
targetContentOffset->x = goodOffsetX;
}
您可以使用以下代码实现自定义分页:
- (float) pageWidth {
return ((UICollectionViewFlowLayout*)self.collectionView.collectionViewLayout).itemSize.width +
((UICollectionViewFlowLayout*)self.collectionView.collectionViewLayout).minimumInteritemSpacing;
}
- (void) scrollViewWillBeginDragging:(UIScrollView *)scrollView {
CGFloat pageWidth = self.collectionView.frame.size.width + 10 /* Optional Photo app like gap between images. Or use [self pageWidth] in case if you want the next page be also visible */;
_currentPage = floor((self.collectionView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
NSLog(@"Dragging - You are now on page %i", _currentPage);
}
- (void) scrollViewWillEndDragging:(UIScrollView*)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint*)targetContentOffset {
CGFloat pageWidth = self.collectionView.frame.size.width + 10; // [self pageWidth]
int newPage = _currentPage;
if (velocity.x == 0) { // slow dragging not lifting finger
newPage = floor((targetContentOffset->x - pageWidth / 2) / pageWidth) + 1;
}
else {
newPage = velocity.x > 0 ? _currentPage + 1 : _currentPage - 1;
if (newPage < 0)
newPage = 0;
if (newPage > self.collectionView.contentSize.width / pageWidth)
newPage = ceil(self.collectionView.contentSize.width / pageWidth) - 1.0;
}
NSLog(@"Dragging - You will be on %i page (from page %i)", newPage, _currentPage);
*targetContentOffset = CGPointMake(newPage * pageWidth, targetContentOffset->y);
}
当然,您必须设置pageingEnabled = NO。_currentPage是iVar类。感谢http://www.mysamplecode.com/2012/12/ios-scrollview-example-with-paging.html指出了正确的方法。
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