iosswiftswiftuiphotophasset

SwiftUI Error : Cannot convert value of type 'UIImage?' to closure result type 'Void'


I get the following SwiftUI error:

var assetImage : UIImage? {
        if PHPhotoLibrary.authorizationStatus() == .authorized {
            let allPhotosOptions = PHFetchOptions()
            allPhotosOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
            let assetsFetchResults = PHAsset.fetchAssets(with: allPhotosOptions)
            if assetsFetchResults.count > 0 {
                let asset = assetsFetchResults.lastObject
                if asset != nil {
                    let options = PHImageRequestOptions()
                    options.isNetworkAccessAllowed = true
                    options.version = .current
                    
                    PHCachingImageManager().requestImage(for: asset!, targetSize: CGSize(width: 64 * UIScreen.main.scale, height: 64 * UIScreen.main.scale), contentMode: .aspectFill, options: options, resultHandler: { img, _ in
                        DispatchQueue.main.async {
                            return img //Error Here
                        }
                    })
                } else {
                    return nil
                }
            } else {
                return nil
            }
        }
        return nil
    }

I get the following error:

Cannot convert value of type 'UIImage?' to closure result type 'Void'

Solution

  • Instead of computed property, change it to a method with completionHandler as you are accessing the image asynchronously from the PHCachingImageManager.

    func assetImage(_ completion: @escaping (UIImage?) -> Void) {
        if PHPhotoLibrary.authorizationStatus() == .authorized {
            let allPhotosOptions = PHFetchOptions()
            allPhotosOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
            let assetsFetchResults = PHAsset.fetchAssets(with: allPhotosOptions)
            if assetsFetchResults.count > 0 {
                let asset = assetsFetchResults.lastObject
                if asset != nil {
                    let options = PHImageRequestOptions()
                    options.isNetworkAccessAllowed = true
                    options.version = .current
                    
                    PHCachingImageManager().requestImage(for: asset!, targetSize: CGSize(width: 64 * UIScreen.main.scale, height: 64 * UIScreen.main.scale), contentMode: .aspectFill, options: options, resultHandler: { img, _ in
                        DispatchQueue.main.async {
                            completion(img)
                        }
                    })
                } else {
                    completion(nil)
                }
            } else {
                completion(nil)
            }
        } else {
            completion(nil)
        }
    }
    

    Usage

        self.assetImage { (image) in
            
        }