Always save screenshot in same custom name app album in "Photos"

Question

I am building an app with button that make screen shot. Now I want to save all screen shots made in this app, in same custom name app album. I already know how to create album just the first time that app opens with code bellow. I am creating my album with Photos framework like:

-(void)createAppAlbum
{

[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetCollectionChangeRequest *changeRequest = [PHAssetCollectionChangeRequest creationRequestForAssetCollectionWithTitle:@"App Album Name"];
    albumPlaceholder = changeRequest.placeholderForCreatedAssetCollection;

}

 completionHandler:^(BOOL success, NSError *error) {
                         if (success) {
                         fetchResult = [PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers:@[albumPlaceholder.localIdentifier] options:nil];
                                          assetCollection = fetchResult.firstObject;

} 
                        else {
                              NSLog(@"Error creating album: %@", error);}
                                  }];

}

So my app creates album named "App Album Name". I am able to take and store my screenshot in my new album with button like:

 -(IBAction)screenshot:(id)sender
{

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, [UIScreen mainScreen].scale);
else
    UIGraphicsBeginImageContext(self.view.bounds.size);

[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();


[[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
    PHAssetChangeRequest *assetChangeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:image];

    PHAssetCollectionChangeRequest *assetCollectionChangeRequest = [PHAssetCollectionChangeRequest changeRequestForAssetCollection:assetCollection];
    [assetCollectionChangeRequest addAssets:@[[assetChangeRequest placeholderForCreatedAsset]]];
} completionHandler:^(BOOL success, NSError *error) {
    if (!success) {
        NSLog(@"Error creating asset: %@", error);
    }
}];

}

In case I leave this viewController, and get back in later, I want to find album that I already created, and save another screen shot in same album, because I don't want to create new one every time I enter this view controller.

So my question is, how would I get album I created first time by Name and then save new screen shots in.

Answer 1

Since this question is specifically targeting, iOS 8, this code will work just fine:

- (void)saveImage:(UIImage *)image {
    if (!self.library) {
        self.library = [[ALAssetsLibrary alloc] init];
    }

    __weak ALAssetsLibrary *lib = self.library;

    [self.library addAssetsGroupAlbumWithName:@"My Photo Album" resultBlock:^(ALAssetsGroup *group) {

        ///checks if group previously created
        if(group == nil){

            //enumerate albums
            [lib enumerateGroupsWithTypes:ALAssetsGroupAlbum
                               usingBlock:^(ALAssetsGroup *g, BOOL *stop)
             {
                 //if the album is equal to our album
                 if ([[g valueForProperty:ALAssetsGroupPropertyName] isEqualToString:@"My Photo Album"]) {

                     //save image
                     [lib writeImageDataToSavedPhotosAlbum:UIImagePNGRepresentation(image) metadata:nil
                                           completionBlock:^(NSURL *assetURL, NSError *error) {

                                               //then get the image asseturl
                                               [lib assetForURL:assetURL
                                                    resultBlock:^(ALAsset *asset) {
                                                        //put it into our album
                                                        [g addAsset:asset];
                                                    } failureBlock:^(NSError *error) {

                                                    }];
                                           }];

                 }
             }failureBlock:^(NSError *error){

             }];

        }else{
            // save image directly to library
            [lib writeImageDataToSavedPhotosAlbum:UIImagePNGRepresentation(image) metadata:nil
                                  completionBlock:^(NSURL *assetURL, NSError *error) {

                                      [lib assetForURL:assetURL
                                           resultBlock:^(ALAsset *asset) {

                                               [group addAsset:asset];

                                           } failureBlock:^(NSError *error) {

                                           }];
                                  }];
        }

    } failureBlock:^(NSError *error) {

    }];
}

To test that this works, I created a single screen application, added a button to the view, and added a method that takes a screenshot and then passes the image to the saveImage: function. Here's the code that I added to it to make it work:

#import <AssetsLibrary/AssetsLibrary.h>

@interface ViewController ()
@property (nonatomic, strong) UIButton *screenshotButton;
@property (nonatomic, strong) ALAssetsLibrary *library;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self.view addSubview:self.screenshotButton];
}

- (UIButton *)screenshotButton {
    if (!_screenshotButton) {
        _screenshotButton = [[UIButton alloc] initWithFrame:CGRectInset(self.view.bounds, 100.0f, 120.0f)];
        _screenshotButton.layer.borderColor = [UIColor blueColor].CGColor;
        _screenshotButton.layer.borderWidth = 2.0f;
        _screenshotButton.layer.cornerRadius = 5.0f;
        [_screenshotButton setTitle:@"Take Screenshot" forState:UIControlStateNormal];
        [_screenshotButton setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
        [_screenshotButton addTarget:self action:@selector(takeScreenshot) forControlEvents:UIControlEventTouchUpInside];
    }

    return _screenshotButton;
}

- (void)takeScreenshot {
    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
        UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, [UIScreen mainScreen].scale);
    else
        UIGraphicsBeginImageContext(self.view.bounds.size);

    [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData * imgData = UIImagePNGRepresentation(image);
    if(imgData)
        [imgData writeToFile:@"screenshot.png" atomically:YES];
    else
        NSLog(@"error while taking screenshot");


    UIColor *randomColor = [UIColor colorWithHue:((CGFloat)(arc4random()%255)/255.0f)
                                      saturation:((CGFloat)(arc4random()%255)/200.0f)
                                      brightness:((CGFloat)(arc4random()%100)/255.0f) + 0.5f
                                           alpha:1.0f];
    self.screenshotButton.layer.borderColor = randomColor.CGColor;
    [self.screenshotButton setTitleColor:randomColor forState:UIControlStateNormal];

    [self saveImage:image];
}

A few things to note:

• AssetsLibrary is deprecated in iOS 9, so it is not recommended to be used after iOS 8, but will still work.
• This can be implemented and used with any UIImage passed to saveImage:, so it can work even if you're using another library.
• Make sure to include #import <AssetsLibrary/AssetsLibrary.h>.
• Change "My Photo Album" to the correct album name, and possibly set that statically