swift4如何使用滤镜更改黑白图像的颜色

import UIKit
import CoreImage

func applyFilterToImage(image: UIImage) -> UIImage? {
    // 将UIImage转换为CIImage
    guard let ciImage = CIImage(image: image) else {
        return nil
    }
    
    // 创建滤镜
    guard let filter = CIFilter(name: "CIColorControls") else {
        return nil
    }
    
    // 设置滤镜参数
    filter.setValue(ciImage, forKey: kCIInputImageKey)
    filter.setValue(1.0, forKey: kCIInputSaturationKey) // 设置饱和度为1，保持彩色
    
    // 获取滤镜输出图像
    guard let outputImage = filter.outputImage else {
        return nil
    }
    
    // 创建CIContext
    let context = CIContext(options: nil)
    
    // 将CIImage转换为CGImage
    guard let cgImage = context.createCGImage(outputImage, from: outputImage.extent) else {
        return nil
    }
    
    // 将CGImage转换为UIImage
    let processedImage = UIImage(cgImage: cgImage)
    
    return processedImage
}

// 使用示例
let originalImage = UIImage(named: "black_white_image.jpg")
let processedImage = applyFilterToImage(image: originalImage)