iOS：CIColorInvert 過濾器在設備上不起作用

Question

這是我反轉圖像的 colors 的代碼塊：

import Foundation
import UIKit
import CoreImage

extension UIImage {
    static let defaultImage = UIImage(systemName: "person.circle.fill")!
    func colorInverted() -> UIImage {
        guard let ciImage = CIImage(image: self) else {
            print("UIImage: Failed to get CIImage!")
            return UIImage.defaultImage
        }
        guard let filter = CIFilter(name: "CIColorInvert") else {
            print("UIImage: Failed to get filter!")
            return UIImage.defaultImage
        }
        filter.setValue(ciImage, forKey: kCIInputImageKey)
        guard let image = filter.outputImage else {
            print("UIImage: Failed to get output image!")
            return UIImage.defaultImage
        }
        return UIImage(ciImage: image)
    }
}

這在模擬器上運行良好：

但在真實設備上，結果是全藍色圖像：

我已經搜索了一段時間，但無法找到解決方案。 任何人都可以幫忙嗎？

注意：我從 GitHub API 獲取圖像：

https://avatars0.githubusercontent.com/u/1?v=4

Answer 1

使用 CIContext 代替 UIImage(CIImage:)

func applyFilter(){
    let image = CIImage(CGImage: myimage.image?.CGImage)
    let filter = CIFilter(name: "CISepiaTone")
    filter.setDefaults()
    filter.setValue(image, forKey: kCIInputImageKey)

    let context = CIContext(options: nil)
    let imageRef = context.createCGImage(filter.outputImage, fromRect: image.extent())
    myimage.image = UIImage(CGImage: imageRef)
}