[英]Scroll programmatically collection view
我有一个水平收集视图。 我想要的是添加一个按钮,并在按下时自动滚动到下一个单元格。 这个怎么做?
我正在尝试这种方法,但是没有用:
- (IBAction)scrollCollection:(id)sender {
NSIndexPath *newIndexPath = [NSIndexPath indexPathForRow:0 inSection:0];
NSArray *indexPaths = [self.notesCollection indexPathsForSelectedItems];
if ( indexPaths.count > 0 )
{
NSIndexPath *oldIndexPath = indexPaths[0];
NSInteger oldRow = oldIndexPath.row;
newIndexPath = [NSIndexPath indexPathForRow:oldRow + 1 inSection:oldIndexPath.section];
}
}
和这个:
- (IBAction)scrollCollection:(id)sender {
UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)[self.notesCollection collectionViewLayout];
[self.notesCollection setPagingEnabled:YES];
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
self.notesCollection.contentOffset = self.scrollingPoint;
// Here you have to respond to user interactions or else the scrolling will not stop until it reaches the endPoint.
if (CGPointEqualToPoint(self.scrollingPoint, self.endPoint)) {
[self.scrollingTimer invalidate];
}
// Going one pixel to the right.
self.scrollingPoint = CGPointMake(self.scrollingPoint.x, self.scrollingPoint.y+1);
}
你可以试试这个
@property (nonatomic, assign) CGPoint scrollingPoint, endPoint;
@property (nonatomic, strong) NSTimer *scrollingTimer;
@synthesize scrollingPoint, endPoint;
@synthesize scrollingTimer;
- (void)scrollSlowly {
// Set the point where the scrolling stops.
self.endPoint = CGPointMake(0, 300);
// Assuming that you are starting at {0, 0} and scrolling along the x-axis.
self.scrollingPoint = CGPointMake(0, 0);
// Change the timer interval for speed regulation.
self.scrollingTimer = [NSTimer scheduledTimerWithTimeInterval:0.015 target:self selector:@selector(scrollSlowlyToPoint) userInfo:nil repeats:YES];
}
- (void)scrollSlowlyToPoint {
self.collectionView.contentOffset = self.scrollingPoint;
// Here you have to respond to user interactions or else the scrolling will not stop until it reaches the endPoint.
if (CGPointEqualToPoint(self.scrollingPoint, self.endPoint)) {
[self.scrollingTimer invalidate];
}
// Going one pixel to the right.
self.scrollingPoint = CGPointMake(self.scrollingPoint.x, self.scrollingPoint.y+1);
}
或者您也可以使用此代码。
NSInteger section = [self numberOfSectionsInCollectionView:collectionView] - 1;
NSInteger item = [self collectionView:collectionView numberOfItemsInSection:section] - 1;
NSIndexPath *lastIndexPath = [NSIndexPath indexPathForItem:item inSection:section];
[collectionView scrollToItemAtIndexPath:lastIndexPath atScrollPosition:UICollectionViewScrollPositionBottom animated:YES];
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