Question

我有一个从故事板连接的按钮，我想按下时将我的水平滚动集合视图向右滚动一个项目。这是我提出的代码：

- (IBAction)rightButton:(id)sender {
    NSIndexPath *indexPath = [self.collectionView indexPathsForSelectedItems];
    NSIndexPath* newIndexPath = [NSIndexPath indexPathForRow:indexPath.row+1 inSection:indexPath.section];


    [self.collectionView scrollToItemAtIndexPath:newIndexPath
                            atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally
                                    animated:YES];

}

但是，这会导致崩溃，错误

 -[__NSArrayI row]: unrecognized selector sent to instance 0x178232540
 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayI row]: unrecognized selector sent to instance 0x178232540'

我怀疑问题是这个代码更适用于TableView，它不喜欢那里的部分停放。

有人可以帮我解决这个问题并弄清楚我为什么会收到错误吗？有更好的方法吗？

由于

Answer 1

indexPathsForSelectedItems方法名称中包含额外的s，Paths不是Path，这表示它返回NSArray个索引路径，而不是单个索引路径。因此，解决方案是改变这些行

NSIndexPath *indexPath = [self.collectionView indexPathsForSelectedItems];
NSIndexPath* newIndexPath = [NSIndexPath indexPathForRow:indexPath.row+1 inSection:indexPath.section];

到这个

NSIndexPath *newIndexPath = [NSIndexPath indexPathForRow:0 inSection:0];

NSArray *indexPaths = [self.collectionView indexPathsForSelectedItems];
if ( indexPaths.count > 0 )
{
    NSIndexPath *oldIndexPath = indexPaths[0];
    NSInteger oldRow = oldIndexPath.row;
    newIndexPath = [NSIndexPath indexPathForRow:oldRow + 1 inSection:oldIndexPath.section];
}

创建一个按钮以滚动UICollectionView

1 个答案: