Implement custom func with completion handler - swift

Question

I have just created a custom class for my purpose (export something to destination).
My extend class as below
import Foundation
import UIKit
class PBExtensionExport: NSObject {
static let instance = PBExtensionExport()
fileprivate var progress: Int = 0
func exportPhotos(images: [UIImage], completion: (Bool) -> ()) {
for image in images {
UIImageWriteToSavedPhotosAlbum(image, self, #selector(updateStatus), nil)
// Progress monitoring
completion(images.count == progress)
}
}
#objc private func updateStatus() {
// Updating progress status
progress += 1
}
}
And this is how I called it in main proc:
PBExtensionExport.instance.exportPhotos(images: selectedImages, completion: { (success) -> Void in
if success {
// Do something
} else {
}
})
The problem is no compile error. But when I run my code, the command display runtime exception:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '-[NSInvocation setArgument:atIndex:]: index (2) out of bounds [-1, 1]'
Can anyone explain this problem for me please?

Answer 1

Your updateStatus takes no arguments while UIImageWriteToSavedPhotosAlbum's completionSelector parameter expects this method signature, according to the docs.
- (void)image:(UIImage *)image
didFinishSavingWithError:(NSError *)error
contextInfo:(void *)contextInfo;
In Swift, this would be something like
func updateStatus(image: UIImage, error: Error?, context: UnsafeRawPointer) {
// Your code here
}

Answer 2

You should go with Photos framework to save images. See below code with proper use of completion handler.
fileprivate var currentImageIndex = 0
typealias imagecompletionBlock = (_ isSuccess: Bool) -> Void
var arrImages:[UIImage]?
var imageSuccessBlock : imagecompletionBlock?
func saveImageToLibrary(images:[UIImage],completion:#escaping ((Bool) -> Void))
{
self.imageSuccessBlock = completion
self.currentImageIndex = 0
}
func saveImage()
{
if self.currentImageIndex == self.arrImages?.count
{
self.imageSuccessBlock!(true)
}else{
PHPhotoLibrary.shared().performChanges({
PHAssetChangeRequest.creationRequestForAsset(from: self.arrImages![self.currentImageIndex])
}, completionHandler: { success, error in
DispatchQueue.main.async {
if success {
// Saved successfully!
self.saveImage()
}
else if let error = error {
// Save photo failed with error
}
else {
// Save photo failed with no error
}
}
})
}
}