Get All Images from cameraroll asynchrously

问题

I want to get all images from cameraroll asynchrously Now I am using that code but my application got hanged untill all the images retrieved , I noticed in instigram or other application it doen't take time to load picture from camerroll.

-(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;
}

回答1:

Try like this .. Its increasing fast speed. If you will get all images in array then it will crashing your application while using iPhone & iPad that contain 1000+ photos. So Try like this.

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");
}];

Show your image in your delegate function like this using this collectionView cellForItemAtIndexPath

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

回答2:

Please use new modern Photos framework which is available from iOS 8.0. I've tested it on 50k photos and 1.5k videos stored in hundreds of albums at my own iCloud Photo Library. It works fast and allows to track and animate changes of albums and assets.

Here is nice article to start with Photos framework: https://www.objc.io/issues/21-camera-and-photos/the-photos-framework/

来源：https://stackoverflow.com/questions/32472262/get-all-images-from-cameraroll-asynchrously