ios - MPMediaItemPropertyArtwork 导致崩溃(奇怪的问题)

Question

运行“额外循环”之前的分配

代码:

// loading items to the array, there are no memory warnings after this is completed. The first allocations screenshot is after this code and before extra loop code.
NSMutableArray *albumCovers = [[NSMutableArray alloc] init];
for (MPMediaQuery *query in queries) {
    NSArray *allCollections = [query collections];
    for (MPMediaItemCollection *collection in allCollections) {
        MPMediaItemArtwork *value = [collection.representativeItem valueForProperty:MPMediaItemPropertyArtwork];
                UIImage *image = [value imageWithSize:CGSizeMake(100, 100)];
                if (image) {
                    [albumCovers addObject:image];
                }
            }
        }
    }
    _mediaCollections = [NSArray arrayWithArray:artworkedCollections];
    _albumCovers = [NSArray arrayWithArray:albumCovers];
}

还有别的地方:

// !!!!! extra loop - from here the memory starts to grow and never release
for (i=0; i< 800; i++) {
    UIImage * coverImage = [_albumCovers objectAtIndex:indexPath.row];
    [veryTemp setImage:coverImage]; // exactly this line adds to the memory. with this line commented, there is no problem.
}

运行“额外循环”后的分配

并澄清一下，在 only-obj-c 打开和系统库关闭的情况下调用堆栈(如果我打开它们，每个最重的方法的最高百分比是 0.9%)

我做了一些研究，并在 stackoverflow 找到了，这些 VM:ImageIO_PNG_Data 通常来自 [UIImage imageNamed:]，但是如您所见，我不使用此方法，我只是获取引用来自 MPMediaItemCollection。

Answer 1

问题是 UIImage 通常只保留一个 ref(CGImageRef)，它很小。显示项目后，CGImageRef 被“注入(inject)”了信息。结果，该表一直在增长。

简单但不是最漂亮的解决方案是使用代码:

NSArray = @[obj1, obj2, obj3]; // where obj is custom NSObject and has a UIImage property

代替:

NSArray = @[img1, img2, img3]; // where img is of UIImage type