Get array of all photos in iOS Photo Gallery with faces in them

Question

I'm trying to go through every photo in an iOS Device's photo library including camera roll, albums, etc..

From there, I want to check if the photo has a face in it, using core image, and if so, add it to an array called detectedFaceArray.

I understand I have to use ALAssetsLibrary to enumerate through all the groups and then photos in the photo gallery, but I have no idea how to implement core image on each photo. The code I am using is the code being asked in this question here:

https://stackoverflow.com/questions/18658783/enumerategroupswithtypes-alassetsgroupall-retrieves-only-the-number-of-photos-i

OR

-(void)getAllPictures
{
self.galleryImages=[[NSMutableArray 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)
{

if(result != nil)
{
    if([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto])
    {
        [assetURLDictionaries addObject:[result valueForProperty:ALAssetPropertyURLs]];

        NSURL *url= (NSURL*) [[result defaultRepresentation]url];

        [library assetForURL:url
                 resultBlock:^(ALAsset *asset) {
                     [mutableArray addObject:asset];
                     if ([mutableArray count]==count)
                     {
                         self.galleryImages=[[NSMutableArray alloc] initWithArray:mutableArray];
                     }
                 }
                failureBlock:^(NSError *error){ NSLog(@"operation was not successfull!"); } ];
    }
}
};

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

void (^ assetGroupEnumerator) ( ALAssetsGroup *, BOOL *)= ^(ALAssetsGroup *group, BOOL *stop) {
    if(group != nil) {
        [group enumerateAssetsUsingBlock:assetEnumerator];
        [assetGroups addObject:group];
        count=[group numberOfAssets];
    }
};

assetGroups = [[NSMutableArray alloc] init];

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

I'm not even sure if this is the correct code to be using so any help would be appreciated. I have read through the ALAssetsLibrary and Core Image Documentation but still don't know how I could do it.

Any suggestions? Thank you!

score 2 · Answer 1 · answered Oct 12 '13 at 09:06

2

I exactly don't know how to detect a face from image. But you can read this link & download OpenCV to do that

answered Oct 12 '13 at 09:06

Akshit Zaveri

4,166
6
30
59

I know how to use Core Image to do it, I just don't know where to put the code to do it...? Thanks for the link though – falky Oct 12 '13 at 11:42
@falky did you ever figure this out? I need to do something similar – michael Dec 18 '13 at 18:59
@michael no I didn't sorry – falky Dec 19 '13 at 12:23

score 0 · Answer 2 · answered Oct 30 '14 at 17:02

For those who still looking for a possible answer to the question. I am using this code to enumerate assets and save those that have faces on them.

[self.library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
                [group setAssetsFilter:[ALAssetsFilter allPhotos]];
                [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {
                    if(result && self.galleryAssets.count <= 20) {
                       CIImage *ciImage = [CIImage imageWithCGImage:result.thumbnail];
                        NSNumber *orientation = [NSNumber numberWithInt:[[UIImage imageWithCIImage:ciImage] imageOrientation]+1];
                        NSDictionary *fOptions = [NSDictionary dictionaryWithObject:orientation forKey: CIDetectorImageOrientation];
                        NSArray *features = [detector featuresInImage:ciImage options:fOptions];

                        if(features.count != 0) {
                            [self.galleryAssets addObject:result];
                        }
                        *stop = NO;
                    } else {
                        *stop = YES; return;
                    }
                }];

                dispatch_async(dispatch_get_main_queue(), ^{
                    if(self.galleryAssets.count == 0) {
                        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"No Photos" message:@"You have no photos in your gallery." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
                        [alert show];
                    } 
                });
            } failureBlock:nil];

Get array of all photos in iOS Photo Gallery with faces in them

2 Answers2