How to set an offset to PHAsset.fetchAssets? - ios

Question

This is my code to fetch images from the device gallery.
let imgManager = PHImageManager.default()
let requestOptions = PHImageRequestOptions()
//loading all the images
requestOptions.isSynchronous = false
//Quality of the image
requestOptions.deliveryMode = .highQualityFormat
//requestOptions.resizeMode = .fast
//Sorted images
let fetchOptions = PHFetchOptions()
fetchOptions.fetchLimit = 500
fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
let fetchResult = PHAsset.fetchAssets(with: .image, options: fetchOptions)
DispatchQueue.global(qos: .background).async {
if fetchResult.count > 0 {
DispatchQueue.main.async {
self.showProgress()
}
for i in 0..<fetchResult.count{
imgManager.requestImage(for: fetchResult.object(at: i) , targetSize: CGSize(width: self.selectedImage.frame.width, height:self.selectedImage.frame.height), contentMode: .aspectFill, options: requestOptions, resultHandler: {
image, error in
if(image == nil){
}else{
self.imageArray.append(image!)
}
})
}
DispatchQueue.main.async {
self.hideProgress()
self.photosCollectionView.reloadData()
}
}else{
self.hideProgress()
self.showDefaultAlert(title: "Alert", message: "Could not fetch images from the gallery")
}
I get memory issues when there are about 1500+ images in the device. I have figured out how to set a limit of how to i get the next 500 images when collection view is scrolled to the bottom? Any help would be much appreciated.

Answer 1

What is the problem you fixing? I think, heavy operation is in requestImage, you can try
fetchResult.objects(at: IndexSet(0...500))
fetchResult.objects(at: IndexSet(501...1000))
etc.
or may be add predicate
fetchOptions.predicate = NSPredicate(format: "#NOT(localIdentifier IN %#)", alreadyGettedIdentifiers)
for i in 0..<fetchResult.count{
let fetchResult = fetchResult.object(at: i)
alreadyGettedIdentifiers.append(fetchResult.localIdentifier)
PHImageManager.default().requestImage(for: fetchResult, targetSize: CGSize(width: 200, height:200), contentMode: .aspectFill, options: requestOptions, resultHandler: {
image, error in
if(image == nil){
}else{
self.imageArray.append(image!)
}
})
}