如何在我的 collectionView 中获取 Moment 相册和所有个人相册？

Question

我正在尝试使用Photos Framework。在我的collectionView 中，我想展示Camera Roll 和Personal albums 的海报图片。

我正在尝试以这种方式实现代码，但我仍然看到每张专辑的图像都相同......我哪里做错了？

我把代码放在这里...希望有人能帮助我

//USER ALBUM
@property (nonatomic, strong) PHFetchResult *userAlbum;
@property (nonatomic, strong) PHAssetCollection *assetCollection;
@property (nonatomic, strong) PHAsset *asset;


-(void)viewDidLoad {
    [super viewDidLoad];

    PHFetchOptions *userAlbumsOptions = [[PHFetchOptions alloc] init];
    userAlbumsOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];

    self.userAlbum = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum | PHAssetCollectionTypeMoment  subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];

    for (NSInteger i =0; i < self.userAlbum.count; i++) {
        self.assetCollection = [self.userAlbum objectAtIndex:i];
        NSLog(@"%@",[self.assetCollection.localizedTitle uppercaseString]);

        PHFetchResult *fetchResult = [PHAsset fetchKeyAssetsInAssetCollection:self.assetCollection options:nil];
        self.asset = [fetchResult firstObject];
 }
}

-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return self.userAlbum.count;
}


-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath {

        KCCategoryCell *catCell = [collectionView dequeueReusableCellWithReuseIdentifier:categoryCellID forIndexPath:indexPath];

        CGFloat retina = [UIScreen mainScreen].scale;
        CGSize square = CGSizeMake(catCell.albumImage.bounds.size.width * retina, catCell.bounds.size.height * retina);

        [[PHImageManager defaultManager] requestImageForAsset:self.asset targetSize:square  contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
                catCell.albumImage.image = result;
        }];

        return catCell;
}

Answer 1

您看到相同图像的原因是因为您为所有索引请求相同的资产：

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath {

    KCCategoryCell *catCell = [collectionView dequeueReusableCellWithReuseIdentifier:categoryCellID forIndexPath:indexPath];

    CGFloat retina = [UIScreen mainScreen].scale;
    CGSize square = CGSizeMake(catCell.albumImage.bounds.size.width * retina, catCell.bounds.size.height * retina);

    [[PHImageManager defaultManager] requestImageForAsset:self.asset // <-- Right here
                                               targetSize:square  contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
        catCell.albumImage.image = result;
    }];

    return catCell;
}

所以不要这样做，而是这样做：

1) 将@property (nonatomic, strong) PHAsset *asset; 更改为@property (nonatomic, strong) PHFetchResult *assets;

2) 而不是这样做：

PHFetchResult *fetchResult = [PHAsset fetchKeyAssetsInAssetCollection:self.assetCollection options:nil];
self.asset = [fetchResult firstObject];

这样做：

self.assets = [PHAsset fetchKeyAssetsInAssetCollection:self.assetCollection options:nil];

3) 最后，不要这样做：

[[PHImageManager defaultManager] requestImageForAsset:self.asset
                                           targetSize:square contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
   catCell.albumImage.image = result;
}];

这样做：

[[PHImageManager defaultManager] requestImageForAsset:self.assets[indexPath.row]
                                           targetSize:square contentMode:PHImageContentModeAspectFill options:nil resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
   catCell.albumImage.image = result;
}];

回顾一下：

您一遍又一遍地为所有单元格获取相同的图像 (self.asset)。因此，改为为所有资产创建一个属性，并为正确的单元格获取正确的资产。