今天做項目的時候需要自定義裁切來自相機圖庫選擇的圖片，找了一圈資料發(fā)現(xiàn)相關的信息甚少。爬了好幾個小時的坑，分享給大家～

開始之前忍不住吐槽一手蘋果，既然系統(tǒng)提供了選取圖片后的裁切功能，讓開發(fā)者傳個CGRect，CGSize進去不應該理所當然嗎？搞得我一開始瘋狂的查水果的 API Reference，最后得出一個無奈的結論。。。寬高定死，你愛用不用：）。。。難道蘋果認為用戶對圖片的需求大小只有那么一種嗎？。。。

其實自定義裁剪器主要就是核心繪圖

1.畫個遮罩出來

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.裁剪圖片（核心部分到這里就結束了）

        let rect  = UIScreen.main.bounds
        
        // 記錄屏幕縮放比
        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，再截圖
        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
        }
        // 關閉上下文
        UIGraphicsEndImageContext()
    }

3.定一個協(xié)議來傳值

protocol SwiftyPhotoClipperDelegate {
    
    func didFinishClippingPhoto(image:UIImage)
}

4.忘了一步，關于圖片的縮放，一個 scrollview ，當他的 maximumZoomScale 和 minimumZoomScale 不同并且實現(xiàn) viewForZooming 返回縮放視圖即可。
代碼很簡單，沒什么好貼的，就貼一個定位代碼吧

func scrollViewDidZoom(_ scrollView: UIScrollView) {
      
      //當捏或移動時，需要對center重新定義以達到正確顯示位置
      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 跳轉到我們的自定義裁剪器即可

//選擇圖片成功后代理
    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～么么噠~