我正在尝试在一个视图中显示多个 UICollectionView。该视图是折叠手风琴样式视图，使用此自定义 AccordionView 控件。
目标是显示图像缩略图的多个部分，其中每个部分包含一个 UICollectionView，如下所示：
数据以self.wallpaperCollectionArray下面的 NSArray 形式提供，其中wallpaper_id是缩略图图像的路径：
(
{
name = "Bold Statement";
"wallpaper_id" = (
"bs-better",
"bs-look-forward",
"bs-now-never",
"bs-stay-hype",
"bs-you-awesome"
);
},
{
name = "Dreamcatcher";
"wallpaper_id" = (
"dc-disney",
"dc-fear",
"dc-paulo",
"dc-quit"
);
},
{
name = "Goods from the good";
"wallpaper_id" = (
"gg-get-hurt",
"gg-jobs",
"gg-lennon",
"gg-oprah"
);
},
{
name = "Random Set";
"wallpaper_id" = (
"rs-face",
"rs-god-knows",
"rs-good",
"rs-holtz",
"rs-positive",
"rs-read",
"rs-think"
);
},
{
name = Traveling;
"wallpaper_id" = (
"tr-miller"
);
}
)
这是我生成 UICollectionView 的代码：
- (void)loadView {
UIView *libraryView = [UIView new];
CGFloat maxWidth = [[UIScreen mainScreen] bounds].size.width;
CGFloat maxHeight = [[UIScreen mainScreen] bounds].size.height;
// Setup accordion
self.libraryAccordionView = [[AccordionView alloc] initWithFrame:CGRectMake(0, 0, maxWidth, maxHeight)];
// Re-usable layout for the UICollectionView(s) inside the for loop
UICollectionViewFlowLayout *layout = [UICollectionViewFlowLayout new];
layout.itemSize = CGSizeMake(thumbnailSize, thumbnailSize);
layout.minimumInteritemSpacing = 0;
layout.minimumLineSpacing = 1;
// Looping through the array contents:
int i = 0;
for(NSDictionary *currentCollectionDictionary in self.wallpaperCollectionArray) {
NSArray *wallpaperIDs = [currentCollectionDictionary valueForKeyPath:@"wallpaper_id"];
NSInteger numberOfWallpapers = [wallpaperIDs count];
// One row contains 4 thumbnails, while each thumbnail's height is 79.
// So, collectionView height = (total item / 4 + 1) * 79
NSInteger collectionViewHeight = (numberOfWallpapers / 4 + 1) * thumbnailSize;
UICollectionView *currentCollectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, maxWidth, collectionViewHeight)
collectionViewLayout:layout];
[currentCollectionView setDataSource:(id)self];
[currentCollectionView setDelegate:(id)self];
NSString *cellIdentifier = [NSString stringWithFormat:@"cell_%d", i];
[currentCollectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:cellIdentifier];
// Trick to let the delegate and data source functions deal with the multiple UICollectionView's
[currentCollectionView setTag:i];
// * --- Create header --- * //
UIButton *currentHeader = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 0, 30)];
NSString *currentHeaderTitle = [currentCollectionDictionary valueForKeyPath:@"name"];
[currentHeader setTitle:currentHeaderTitle forState:UIControlStateNormal];
[self.libraryAccordionView addHeader:currentHeader withView:currentCollectionView];
i++;
}
[libraryView addSubview:self.libraryAccordionView]
[self setView:libraryView];
}
数据源方法：
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
NSInteger index = collectionView.tag;
NSInteger numberOfWallpaper = [[[self.wallpaperCollectionArray objectAtIndex:index] valueForKeyPath:@"wallpaper_id"] count];
NSLog(@"index is: %d --- # of item is: %d", index, numberOfWallpaper);
return numberOfWallpaper;
}
// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
NSInteger index = collectionView.tag;
NSString *cellIdentifier = [NSString stringWithFormat:@"cell_%d", index];
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier
forIndexPath:indexPath];
NSString *thumbnailName = [[[self.wallpaperCollectionArray objectAtIndex:index] valueForKeyPath:@"wallpaper_id"] objectAtIndex:indexPath.row];
UIImageView *wallpaperImage = [[UIImageView alloc] initWithImage:[UIImage imageNamed:thumbnailName]];
[cell addSubview:wallpaperImage];
return cell;
}
问题是，所有 UICollectionView 都只显示一个缩略图，尽管它们似乎正在加载正确的缩略图：
起初我意识到问题可能出在- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section方法上。
但是，在这个测试NSLog(@"index is: %d --- # of item is: %d", index, numberOfWallpaper);中，结果numberOfWallpaper是正确的：
2013-10-04 08:50:43.992 quo.mk.e[15046:11603] index is: 4 --- # of item is: 1
2013-10-04 08:50:43.993 quo.mk.e[15046:11603] index is: 3 --- # of item is: 7
2013-10-04 08:50:43.994 quo.mk.e[15046:11603] index is: 2 --- # of item is: 4
2013-10-04 08:50:43.994 quo.mk.e[15046:11603] index is: 1 --- # of item is: 4
2013-10-04 08:50:43.995 quo.mk.e[15046:11603] index is: 0 --- # of item is: 5
所以，我返回正确数量的缩略图numberOfItemsInSection。但是，为什么 UICollectionView 只显示一个缩略图？