iOS：CIColorInvert 过滤器在设备上不起作用

Question

这是我反转图像的 colors 的代码块：

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)
    }
}

这在模拟器上运行良好：

但在真实设备上，结果是全蓝色图像：

我已经搜索了一段时间，但无法找到解决方案。 任何人都可以帮忙吗？

注意：我从 GitHub API 获取图像：

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)
}