Write following code in .h file
Add first the assets library framework from BuildPhase -> Link Binary with libraries
import framework in .h

 AssetsLibrary/AssetsLibrary.h

Declare properties

@property (nonatomic, retain) ALAssetsGroup assetsGroup;
@property (nonatomic,strong)NSMutableArray assetsArray;
@property (nonatomic, retain) ALAssetsLibrary* assetLibrary;

Write this code in .m file // Call this below mentioned function in your viewWillAppear
-(void)getAllPictures
{
self.assetsArray = [[NSMutableArray alloc]init];
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
self.assetLibrary = library;
NSMutableArray *groups = [NSMutableArray array];
[assetLibrary enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
if (group) {
[groups addObject:group];
} else {
// this is the end
[self displayPickerForGroup:[groups objectAtIndex:0]];
}
} failureBlock:^(NSError *error) {
UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Error" message:[NSString stringWithFormat:@"Album Error: %@ - %@", [error localizedDescription], [error localizedRecoverySuggestion]] delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil]; [alert show];

    NSLog(@"A problem occurred %@", [error description]);
    // an error here means that the asset groups were inaccessible.
    // Maybe the user or system preferences refused access.
}];

} //=========================================================================== - (void)displayPickerForGroup:(ALAssetsGroup *)group
{
self.assetsGroup = group;
[self.assetsGroup setAssetsFilter:[ALAssetsFilter allAssets]];
[self preparePhotos];
}
//=========================================================================== -(void)preparePhotos{

[self.assetsGroup enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

    if(result == nil) {

        return;

    }

    [self.assetsArray addObject:result];

}];

[self allPhotosCollected:self.assetsArray];

}
//============================================================================ -(void)allPhotosCollected:(NSMutableArray*)imgArray
{
//write your code here after getting all the photos from library...
NSLog(@"%@", imgArray);
}