问题描述
我的项目有一个UIcollectionView.此水平分页并具有四个对象.我想要我的收藏查看自动滚动分页.哪种使用方法?
my project have a UIcollectionView. This Horizontal paging and have four object. i’m want my collectionView Auto Scroll Paging. which use methods?
推荐答案
至于理论，我只是解释关键点.例如，如果您想在某个位置自动循环显示5张图像，就像广告栏一样.您可以创建一个包含100个部分的UICollectionView，每个部分有5个项目.创建UICollectionView后，将其原始位置设置为第50个第0个项目(MaxSections的中间))，以便您可以向左或向右滚动.不必担心它会结束，因为在计时器运行时，我已将位置重置为与MaxSections的中间位置相等.永远不要跟我争论:当用户继续滚动时，它也将结束".如果发现只有5张图像，他会继续滚动吗?我相信这个世界上很少有如此愚蠢的用户！
As for theory, I just explain the key point. For example, if you want to auto-cycle display 5 images in somewhere, just as ads bar. You can create a UICollectionView with 100 sections, and there're 5 items in every section. After creating UICollectionView, set its original position is equal to the 50th section 0th item(middle of MaxSections) so that you can scroll to left or right. Don't worry it will ends, because I have reset the position equal to middle of MaxSections when the Timer runs. Never argue with me :" it also will ends when the user keep scrolling by himself" If one find there're only 5 images, will he keep scrolling!? I believe there is few such silly user in this world!
注意:在以下代码中，headerView是UICollectionView，headerNews是数据.我建议将MaxSections设置为100.
Note： In the following codes，the headerView is UICollectionView，headerNews is data. And I suggest set MaxSections = 100.
在自定义collectionView之后添加NSTimer(确保首先正确设置UICollectionViewFlowLayout):
Add a NSTimer after custom collectionView(Ensure the UICollectionViewFlowLayout is properly set at first):
- (void)addTimer
{
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:3.0f target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
self.timer = timer;
}
然后实现@selector(nextPage):
then implement @selector(nextPage):
- (void)nextPage
{
// 1.back to the middle of sections
NSIndexPath *currentIndexPathReset = [self resetIndexPath];
// 2.next position
NSInteger nextItem = currentIndexPathReset.item + 1;
NSInteger nextSection = currentIndexPathReset.section;
if (nextItem == self.headerNews.count) {
nextItem = 0;
nextSection++;
}
NSIndexPath *nextIndexPath = [NSIndexPath indexPathForItem:nextItem inSection:nextSection];
// 3.scroll to next position
[self.headerView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
}
最后实现resetIndexPath方法:
last implement resetIndexPath method:
- (NSIndexPath *)resetIndexPath
{
// currentIndexPath
NSIndexPath *currentIndexPath = [[self.headerView indexPathsForVisibleItems] lastObject];
// back to the middle of sections
NSIndexPath *currentIndexPathReset = [NSIndexPath indexPathForItem:currentIndexPath.item inSection:MaxSections / 2];
[self.headerView scrollToItemAtIndexPath:currentIndexPathReset atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
return currentIndexPathReset;
}
为了控制NSTimer，您必须实现一些其他方法和UIScrollView的委托方法:
In order to control NSTimer , you have to implement some other methods and UIScrollView's delegate methods:
- (void)removeTimer
{
// stop NSTimer
[self.timer invalidate];
// clear NSTimer
self.timer = nil;
}
// UIScrollView' delegate method
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
[self removeTimer];
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
[self addTimer];
}
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