とりあえず↓のような感じになりました。 extension Image where Pixel == RGBA<UInt8> { public init(uiImage: UIImage) { #if os(iOS) || os(tvOS) if let cgImage = uiImage.cgImage { self.init(cgImage: cgImage) } else if let ciImage = uiImage.ciImage { let context = CIContext() // This `guard` can be replaced with `!` if you are sure that the `createCGImage` below never fails. guard let cgImage = context.createCGImage(ciImage, from: ciImage.extent) else { fatalError("Failed to create a `CGImage` from an internal `CIImage` object from this `UIImage` instance: \(uiImage)") } self.init(cgImage: cgImage) } else { // This `gurad` can be replaced with `assert` if you are sure that the `size` is always equal to `.zero`. guard uiImage.size == .zero else { fatalError("The `size` of this `UIImage` instance (\(uiImage)) is not equal to `.zero` though both `cgImage` and `ciImage` of the instance are `nil`.") } self.init(width: 0, height: 0, pixels: []) } #else if let cgImage = uiImage.cgImage { self.init(cgImage: cgImage) } else { // This `gurad` can be replaced with `assert` if you are sure that the `size` is always equal to `.zero`. guard uiImage.size == .zero else { fatalError("The `size` of this `UIImage` instance (\(uiImage)) is not equal to `.zero` though `cgImage` of the instance is `nil`.") } self.init(width: 0, height: 0, pixels: []) } #endif }
#if で } else if ... { を落とすことができなくて悲しい・・・。
