ALAssetsLibrary 太慢 - Objective-C

Question

从相机胶卷中加载 10-20 张全屏图像、保存照片的快速方法是什么？

我正在使用此代码，但要加载 10 张照片，我需要等待大约 5-10 秒。我用的是 iPhone 4S。

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
    if(_savedPhotos.count>=11) *stop = YES;
    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *result, NSUInteger index, BOOL *needToStop) {
        NSLog(@"%d",index);
        if(_savedPhotos.count<11)
        {
            UIImage *image = [UIImage imageWithCGImage:result.defaultRepresentation.fullScreenImage];
            [_savedPhotos addObject:image];
        }
        else
        {
            *needToStop = YES;
        }
    }];
} failureBlock:^(NSError *error) {
    NSLog(@"%@",error.description);
}];

Answer 1

ALAssetsLibrary 库将在单独的 线程上运行。所以与UI相关的东西和其他东西沟通可能需要一些时间。

所以在 ALAssetsLibrary 块中使用 -performSelectorOnMainThread:withObject:waitUntilDone:。

如下更改您的代码

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *result, NSUInteger index, BOOL *needToStop) {
            NSLog(@"%d",index);
            UIImage *image = [UIImage imageWithCGImage:result.defaultRepresentation.fullScreenImage];
            [self performSelectorOnMainThread:@selector(usePhotolibraryimage:) withObject:image waitUntilDone:NO];
        }];
    }

    failureBlock:^(NSError *error) {
           NSLog(@"%@",error.description);
    }];

- (void)usePhotolibraryimage:(UiImage *)myImage{

    //Do your all UI related and all stuff here
}

注意：看this issue too。