Swift 自定义 UIImagePickerController 选取图片后的裁剪器（相机裁剪界面）

今天做项目的时候需要自定义裁切来自相机图库选择的图片，找了一圈资料发现相关的信息甚少。爬了好几个小时的坑，分享给大家～

开始之前忍不住吐槽一手苹果，既然系统提供了选取图片后的裁切功能，让开发者传个CGRect，CGSize进去不应该理所当然吗？搞得我一开始疯狂的查水果的 API Reference，最后得出一个无奈的结论。。。宽高定死，你爱用不用：）。。。难道苹果认为用户对图片的需求大小只有那么一种吗？。。。

其实自定义裁剪器主要就是核心绘图

1.画个遮罩出来

IMG_0369.PNG

  UIGraphicsBeginImageContextWithOptions(UIScreen.main.bounds.size, false, 0)
        
        let context = UIGraphicsGetCurrentContext()
        context?.setFillColor(UIColor.init(red: 0, green: 0, blue: 0, alpha: 0.5).cgColor)
        context?.fill(UIScreen.main.bounds)
        context?.addRect(CGRect(x: 0, y: (HEIGHT - selectHeight)/2, width: WIDTH , height: selectHeight))
        context?.setBlendMode(.clear)
        context?.fillPath()
        
        
        let img = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        let selectarea = UIImageView(image: img)
        selectarea.frame.origin = CGPoint(x: 0, y: 0)
        view.addSubview(selectarea)

2.裁剪图片（核心部分到这里就结束了）

        let rect  = UIScreen.main.bounds
        
        // 记录屏幕缩放比
        let scal = UIScreen.main.scale
        
        // 上下文
        UIGraphicsBeginImageContextWithOptions(rect.size, true, 0)
        
        let context = UIGraphicsGetCurrentContext()
        
        UIApplication.shared.keyWindow?.layer.render(in: context!)
        
        // 截全屏，再截图
        guard let img = UIGraphicsGetImageFromCurrentImageContext()?.cgImage,
            let result = img.cropping(to: CGRect(x: 0, y: (HEIGHT - selectHeight)/2 * scal, width: self.WIDTH * scal, height: selectHeight * scal))   else{
                return nil
        }
        // 关闭上下文
        UIGraphicsEndImageContext()
    }

3.定一个协议来传值

protocol SwiftyPhotoClipperDelegate {
    
    func didFinishClippingPhoto(image:UIImage)
}

4.忘了一步，关于图片的缩放，一个 scrollview ，当他的 maximumZoomScale 和 minimumZoomScale 不同并且实现 viewForZooming 返回缩放视图即可。
代码很简单，没什么好贴的，就贴一个定位代码吧

func scrollViewDidZoom(_ scrollView: UIScrollView) {
      
      //当捏或移动时，需要对center重新定义以达到正确显示位置
      var centerX = scrollView.center.x
      var centerY = scrollView.center.y
      centerX = scrollView.contentSize.width > scrollView.frame.size.width ? scrollView.contentSize.width / 2 : centerX
      centerY = scrollView.contentSize.height > scrollView.frame.size.height ?scrollView.contentSize.height / 2 : centerY
      self.imgView?.center = CGPoint(x: centerX, y: centerY)   
  }

5.然后就是使用了，在 didFinishPickingMediaWithInfo 中 跳转到我们的自定义裁剪器即可

//选择图片成功后代理
    func imagePickerController(_ picker: UIImagePickerController,didFinishPickingMediaWithInfo info: [String : Any]) {
        if let image = info[UIImagePickerControllerOriginalImage] as? UIImage {
            picker.dismiss(animated: false, completion: { 
                let clipper = SwiftyPhotoClipper()
                clipper.delegate = self
                clipper.img = image
                self.present(clipper, animated: true, completion: nil)
            })
        } else{
            print("Something went wrong")
        }
    }

完整demo：https://github.com/KFCFans/SwiftyPhotoClipper

求 Star 啦～么么哒~