Displaying photo library images in UICollectionView - ios

Question

I am trying to display images from Photo Library in UICollectionView through ALAssetsLibrary my codes runs fine , but I have some issues .
The quality of thumbnails are poor .
How can arrange collection view show 100 recent photos by ordering
from
new to old .
here is my codes :
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// collect the photos
NSMutableArray *collector = [[NSMutableArray alloc] initWithCapacity:0];
ALAssetsLibrary *al = [ViewController defaultAssetsLibrary];
[al enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
usingBlock:^(ALAssetsGroup *group, BOOL *stop)
{
[group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop)
{
if (asset) {
[collector addObject:asset];
}
}];
self.photos = collector;
}
failureBlock:^(NSError *error) { NSLog(#"error");}];
}
-(void)setPhotos:(NSArray *)photos {
if (_photos != photos) {
_photos = photos;
[_collectionView reloadData];
}
}
+ (ALAssetsLibrary *)defaultAssetsLibrary {
static dispatch_once_t pred = 0;
static ALAssetsLibrary *library = nil;
dispatch_once(&pred, ^{
library = [[ALAssetsLibrary alloc] init];
});
return library;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return _photos.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier = #"Cell";
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
UIImageView *collectionImageView = (UIImageView *)[cell viewWithTag:100];
ALAsset *asset = [self.photos objectAtIndex:indexPath.row];
UIImage* img = [UIImage imageWithCGImage:asset.thumbnail];
img = [UIImage imageWithCGImage:img.CGImage scale:2.0 orientation:UIImageOrientationUp];
[collectionImageView setImage:img];
return cell;
}

Answer 1

Use the following code to sort the photos.
self.photos = [collector sortedArrayUsingComparator:^NSComparisonResult(ALAsset *first, ALAsset *second) {
NSDate * date1 = [first valueForProperty:ALAssetPropertyDate];
NSDate * date2 = [second valueForProperty:ALAssetPropertyDate];
return [date1 compare:date2];
}];

Answer 2

You can get the date of an image saved in the library by:
NSDate * date = [asset valueForProperty:ALAssetPropertyDate];
You can compare this date with today's date, and store it an array, and do the same for the 100 Images.
And to your other question,
The thumbnail img you get from asset is of different size depends on iOS. In iOS 9 it is of 75x75 and in iOS 8, it is of 150x150.
You can try this:
[UIImage imageWithCGImage:[asset aspectRatioThumbnail]