在CIImage周围绘制边框

import CoreImage
import UIKit

func addBorderToCIImage(ciImage: CIImage, borderWidth: CGFloat, borderColor: UIColor) -> UIImage? {
    guard let cgImage = CIContext().createCGImage(ciImage, from: ciImage.extent) else {
        return nil
    }
    
    UIGraphicsBeginImageContextWithOptions(ciImage.extent.size, false, 0.0)
    guard let context = UIGraphicsGetCurrentContext() else {
        return nil
    }
    
    // 绘制CIImage
    context.draw(cgImage, in: ciImage.extent)
    
    // 绘制边框
    context.setStrokeColor(borderColor.cgColor)
    context.setLineWidth(borderWidth)
    context.stroke(ciImage.extent)
    
    // 获取最终图像
    let finalImage = UIGraphicsGetImageFromCurrentImageContext()
    
    UIGraphicsEndImageContext()
    
    return finalImage
}

// 使用示例
let ciImage = CIImage(image: UIImage(named: "image.jpg")!)
let borderedImage = addBorderToCIImage(ciImage: ciImage, borderWidth: 5.0, borderColor: .red)

// 将borderedImage显示在UIImageView中或保存到相册中等操作