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

Question

我收到以下 SwiftUI 错误：

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
    }

我收到以下错误：

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

Answer 1

代替计算属性，将其更改为使用 completionHandler 的方法，因为您从 PHCachingImageManager.

异步访问图像

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)
    }
}

用法

    self.assetImage { (image) in
        
    }

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

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

photo

ios

swift

phasset

swiftui