ios - 访问 ALAssetsLibrary 时出现内存错误

Question

我遇到内存错误。我收到内存错误，因为内存使用量呈指数增长。显然我不会发布任何东西，你知道那可能是什么吗？

这是我确定 UI 图像中存在的红色像素的方法。它返回计数。

- (NSUInteger)getRedPixelCount:(UIImage*)image
{
NSUInteger numberOfRedPixels = 0;

struct pixel* pixels = (struct pixel*) calloc(1, image.size.width * image.size.height * sizeof(struct pixel));
if (pixels != nil)
{
    CGContextRef context = CGBitmapContextCreate((void *) pixels,
                                                 image.size.width,
                                                 image.size.height,
                                                 8,
                                                 image.size.width * 4,
                                                 CGImageGetColorSpace(image.CGImage),
                                                 (CGBitmapInfo)kCGImageAlphaPremultipliedLast);

    if (context != NULL)
    {
        CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), image.CGImage);
        NSUInteger numberOfPixels = image.size.width * image.size.height;

        while (numberOfPixels > 0) {
            if (pixels->r == 255) {
                numberOfRedPixels++;

            } 
            pixels++;
            numberOfPixels--;
        }
        CGContextRelease(context);
    }
}
return numberOfRedPixels;

}

这是迭代照片库图像并确定每个红色像素的代码。

[self.library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
    if (group) {
        [group setAssetsFilter:[ALAssetsFilter allPhotos]];
        [group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop){

            if (asset) {
                ALAssetRepresentation *rep = [asset defaultRepresentation];
                CGImageRef iref = [rep fullResolutionImage];

                if (iref){

                        UIImage *myImage = [UIImage imageWithCGImage:iref scale:[rep scale] orientation:(UIImageOrientation)[rep orientation]];

                        NSLog(@"%i", [self getRedPixelCount:myImage]);
                }
            }
        }];
    }
} failureBlock:^(NSError *error) {
    NSLog(@"error enumerating AssetLibrary groups %@\n", error);
}];

问候，C.

Answer 1

你没有释放由

分配的内存

struct pixel* pixels = (struct pixel*) calloc(1, image.size.width * image.size.height * sizeof(struct pixel));

你需要添加:

free(pixels);

在 if(pixels != nil) block 的底部。

让第一个 block 看起来像:

- (NSUInteger)getRedPixelCount:(UIImage*)image
{
    NSUInteger numberOfRedPixels = 0;

    struct pixel* pixels = (struct pixel*) calloc(1, image.size.width * image.size.height * sizeof(struct pixel));
    if (pixels != nil)
    {
        CGContextRef context = CGBitmapContextCreate((void *) pixels,
                                                     image.size.width,
                                                     image.size.height,
                                                     8,
                                                     image.size.width * 4,
                                                     CGImageGetColorSpace(image.CGImage),
                                                     (CGBitmapInfo)kCGImageAlphaPremultipliedLast);

        if (context != NULL)
        {
            CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), image.CGImage);
            NSUInteger numberOfPixels = image.size.width * image.size.height;
            struct pixels* ptr = pixels;

            while (numberOfPixels > 0) {
                if (ptr->r == 255) {
                    numberOfRedPixels++;

                } 
                ptr++;
                numberOfPixels--;
            }
            CGContextRelease(context);
        }
        free(pixels);
    }
    return numberOfRedPixels;
}

如果第二个 block 更改为包括:

        @autoreleasepool {
            ALAssetRepresentation *rep = [asset defaultRepresentation];
            CGImageRef iref = [rep fullResolutionImage];

            if (iref){

                UIImage *myImage = [UIImage imageWithCGImage:iref scale:[rep scale] orientation:(UIImageOrientation)[rep orientation]];

                NSLog(@"%i", [self getRedPixelCount:myImage]);
                <#statements#>
            }
        }

虽然主要泄漏不是释放像素缓冲区。