PHImagemanager requestImageForAsset memory issue - xcode

Question

I want to use PHImagemanager to get all photos on the device.
If I set the targetsize too high the app will crash because of memory warnings. So I tested the request without any use of the returned images and set each image to nil, but still app is crashing. I don't know what I'm doing wrong. Can someone help please?
requestOptions = [[PHImageRequestOptions alloc] init];
requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
requestOptions.synchronous = false;
assetsOfPhotos = [PHAsset fetchAssetsWithMediaType: PHAssetMediaTypeImage options: nil];
PHImageManager *manager = [PHImageManager defaultManager];
#autoreleasepool {
for (int i = 0; i <= totalImages - 1; i++) {
PHAsset *asset = assetsOfPhotos[i];
[manager requestImageForAsset: asset
targetSize: CGSizeMake(640, 480)
contentMode: PHImageContentModeDefault
options: requestOptions
resultHandler: ^void(UIImage *image, NSDictionary *info) {
image = nil;
}];
}
}
Setting size to 640x480 crash after about 200 images, 320x240 after about 800 images. As a 640x480 image needs 4 times memory then 320x240 image it seems that the app crashes after the same amount of memory that was allocated. So for me this means that I cannot show more images than 200 imags with 640x480 on the test device, because I cannot free allocated memory.

Answer 1

In order to make your #autoreleasepool work you need to set requestOptions.synchronous to YES, and use your own async queue if you want to make the request operation asynchronously.

Answer 2

Please use #autoreleasepool inside the for loop.
for (int i = 0; i <= totalImages - 1; i++) {
#autoreleasepool {
//Your code
}
}

Answer 3

If you want load all photos that you have in Photos.app and you didn't want iCloud. You can do:
That example works with a collection view.
#interface GalleryViewModel ()
#property (strong, nonatomic) NSMutableArray<PHAsset *> *assets;
#property (strong, nonatomic) PHImageManager *imageManager;
#property (strong, nonatomic) PHImageRequestOptions *requestOptions;
#property (strong, nonatomic) NSMutableArray<UIImage *> *imagesList;
#end
#implementation GalleryViewModel
- (instancetype) initWithContext:(ITXAppContext *)context {
self = [super initWithContext:context];
if (self) {
_assets = [[NSMutableArray alloc] init];
_imageManager = [PHImageManager defaultManager];
_requestOptions = [[PHImageRequestOptions alloc] init];
_imagesList = [[NSMutableArray alloc] init];
}
return self;
}
#pragma mark - Public methods
// ==================================================================================
// Public methods
- (void) viewModelDidLoad {
[self obtainAllPhotos];
}
#pragma mark - Private methods
// ==================================================================================
// Private methods
- (void) obtainAllPhotos {
self.requestOptions.resizeMode = PHImageRequestOptionsResizeModeExact;
self.requestOptions.deliveryMode = PHImageRequestOptionsDeliveryModeHighQualityFormat;
self.requestOptions.synchronous = YES;
self.requestOptions.networkAccessAllowed = NO;
PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = #[[NSSortDescriptor sortDescriptorWithKey:#"creationDate" ascending:NO]];
PHFetchResult<PHAsset *> *result = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:fetchOptions];
__weak GalleryViewModel *weakSelf = self;
[result enumerateObjectsUsingBlock:^(PHAsset * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
[weakSelf.assets addObject:obj];
if (idx >= ([result count] - 1)) {
[weakSelf.viewDelegate setupView];
}
}];
}
#pragma mark - Get data from object
// ==================================================================================
// Get data from object
- (NSInteger) sizeGallery {
if (self.assets) {
return [self.assets count];
}
return 0;
}
- (UIImage *) imagesFromList:(NSInteger) index {
__block UIImage *imageBlock;
[self.imageManager requestImageForAsset:[self.assets objectAtIndex:index] targetSize:CGSizeMake(200, 200) contentMode:PHImageContentModeAspectFit options:self.requestOptions resultHandler:^(UIImage * _Nullable result, NSDictionary * _Nullable info) {
if (result) {
imageBlock = result;
}
}];
return imageBlock;
}
#end