         cameraPreview.layer.addSublayer(previewLayer!)
         cameraPreview.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(saveToCamera)))
         
+        let line = CustomLine()
+        line.frame = (previewLayer?.frame)!
+        line.backgroundColor = UIColor.clear
+        cameraPreview.addSubview(line)
         
         
         let btnTakePicture = UIButton()

        btnFlashMode.setImage(UIImage(named: "Camera.bundle/btn_camera_flash_auto"), for: .normal)
        
        btnFlashMode.bounds = CGRect(x: 0, y: 0, width: 40, height: 40)
        btnFlashMode.center = CGPoint(x: self.view.frame.width-btnFlashMode.bounds.width/2-20, y: btnFlashMode.bounds.height/2 + 20)
        btnFlashMode.addTarget(self, action: #selector(btnFlashModeAction), for: .touchUpInside)
        
        

import UIKit
import AVFoundation

class CustomLine: UIView{
    override func draw(_ rect: CGRect) {
        
        let context = UIGraphicsGetCurrentContext()!
        
        context.setLineCap(.round)
        context.setLineWidth(1);  //线宽
        context.setAllowsAntialiasing(true);
        context.setStrokeColor(red: 70.0 / 255.0, green: 241.0 / 255.0, blue: 241.0 / 255.0, alpha: 0.6);  //线的颜色
        context.beginPath();
        
        context.move(to: CGPoint(x: 30, y: 0))   //起点坐标
        context.addLine(to: CGPoint(x: 30, y: self.frame.size.height))   //终点坐标
        
        context.move(to: CGPoint(x: 0, y: 30))   //起点坐标
        context.addLine(to: CGPoint(x: self.frame.size.width, y: 30))   //终点坐标
        
        context.move(to: CGPoint(x: self.frame.size.width - 30, y: 0))   //起点坐标
        context.addLine(to: CGPoint(x: self.frame.size.width - 30, y: self.frame.size.height))   //终点坐标
        
        context.strokePath();
    
    }
}

class ViewController: UIViewController {
    
    let captureSession = AVCaptureSession()
