从相机胶卷异步获取所有图像

Question

我想异步地从 cameroll 获取所有图像现在我正在使用该代码，但我的应用程序被挂起，直到检索到所有图像，我注意到在 instigram 或其他应用程序中它不需要时间从 camerroll 加载图片。

-(void)getAllPictures
{

    NSLog(@"i m in ");

    imageArray=[[NSArray alloc] init];
    mutableArray =[[NSMutableArray alloc]init];
    NSMutableArray* assetURLDictionaries = [[NSMutableArray alloc] init];
        library = [[ALAssetsLibrary alloc] init];
        void (^assetEnumerator)( ALAsset *, NSUInteger, BOOL *) = ^(ALAsset *result, NSUInteger index, BOOL *stop) {

            NSLog(@"i m in block");
        if(result != nil) {
            if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {


                NSLog(@"result not nill");


                [assetURLDictionaries addObject:[result valueForProperty:ALAssetPropertyURLs]];

                NSURL *url= (NSURL*) [[result defaultRepresentation]url];
                NSLog(@"url=%@",url);
                [library assetForURL:url
                         resultBlock:^(ALAsset *asset) {
                             [mutableArray addObject:[UIImage imageWithCGImage:[[asset defaultRepresentation] fullScreenImage]]];





                             imageArray=[[NSArray alloc] initWithArray:mutableArray];
                             [self allPhotosCollected:imageArray];


                             if ([mutableArray count]==count)
                             {NSLog(@"condition %lu , %i",(unsigned long)mutableArray.count,count);


                                 imageArray=[[NSArray alloc] initWithArray:mutableArray];
                                 [self allPhotosCollected:imageArray];
                             }
                         }
                        failureBlock:^(NSError *error){ NSLog(@"operation was not successfull!"); } ];

            }
        }
    };


    NSLog(@"image array= %@",imageArray);

    NSMutableArray *assetGroups = [[NSMutableArray alloc] init];

    void (^ assetGroupEnumerator) ( ALAssetsGroup *, BOOL *)= ^(ALAssetsGroup *group, BOOL *stop) {
        if(group != nil) {


            NSLog(@"group not nill");
            [group enumerateAssetsUsingBlock:assetEnumerator];
            [assetGroups addObject:group];
            count=(int)[group numberOfAssets];
        }
    };

    assetGroups = [[NSMutableArray alloc] init];

    [library enumerateGroupsWithTypes:ALAssetsGroupAll
                           usingBlock:assetGroupEnumerator
                         failureBlock:^(NSError *error) {NSLog(@"There is an error");}];
}

-(void)allPhotosCollected:(NSArray*)imgArray
{
    //write your code here after getting all the photos from library...
    NSLog(@"all pictures are %@",imgArray);
    [_collection_view reloadData];



   /*
    CGRect collectionFrame = self.collection_view.frame;

    collectionFrame.size.height=700;
    collectionFrame.size.width=320;*/

self.verticalLayoutConstraint.constant = 700;
    //self.collection_view.frame=collectionFrame;
}

Answer 1

这样试试..它的增加速度很快。如果您将获得数组中的所有图像，那么在使用包含 1000 多张照片的 iPhone 和 iPad 时，它会使您的应用程序崩溃。所以像这样尝试。

library = [[ALAssetsLibrary alloc] init];

if (library == nil)
    library = [[ALAssetsLibrary alloc] init];

[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop)
{

    [group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop)
     {
         if (asset)
         {
             [imageArray addObject:asset];
             [collectionViewObj reloadData];
         }
     }];
 }
                failureBlock:^(NSError *error) 
{
    UIAlertView *alertViewObj = [[UIAlertView alloc]initWithTitle:@"Max6Miz does not have access to your photos" message:@"You can enable access in Settings" delegate:self cancelButtonTitle:nil otherButtonTitles:@"Settings",@"Ok", nil];
    [alertViewObj show];
    NSLog(@"error");
}];

使用此 collectionView cellForItemAtIndexPath

在您的委托函数中显示您的图像

ALAsset *asset = (ALAsset *)imageArray[indexPath.row];
UIImage *showingImage = [UIImage imageWithCGImage:[asset thumbnail]];

Answer 2

请使用 iOS 8.0 提供的新现代 Photos framework。我已经在我自己 iCloud Photo Library 的数百个相册中存储的 50k 照片和 1.5k 视频上对其进行了测试。它工作速度很快，可以跟踪和动画化专辑和资产的变化。

这是一篇很好的文章，可以从 Photos framework 开始：https://www.objc.io/issues/21-camera-and-photos/the-photos-framework/

从相机胶卷异步获取所有图像

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