ios開發之Swift二維碼QRCode的讀取（從圖片讀取 ，或通過網路攝影機掃描）

1，直接讀取圖片中的二維碼

使用 CIDetector 可以很方便的檢測並讀取二維碼。下面是一個從 UIImage 中讀取二維碼的範例，我們要把圖片上所有的二維碼資訊都列印出來。

 

代碼如下

複製代碼

import UIKit   class ViewController: UIViewController {       override func viewDidLoad() {         super.viewDidLoad()           let qrcodeImg =  UIImage(named: "codeBg.png")         let ciImage:CIImage=CIImage(image:qrcodeImg!)!                   let context = CIContext(options: nil)         let detector:CIDetector=CIDetector(ofType: CIDetectorTypeQRCode,             context: context, options: [CIDetectorAccuracy:CIDetectorAccuracyHigh])                   let features=detector.featuresInImage(ciImage)                   print("掃描到二維碼個數：\(features.count)")         //遍曆所有的二維碼，並框出         for feature in features as! [CIQRCodeFeature] {             print(feature.messageString)         }     }       override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }

控制台輸出如下：
掃描到二維碼個數：2
http://www.111cn.net
http://www.111cn.net
可以看到兩個二維碼都成功的讀取到了。

（註：這個我原來用模擬器一直檢測不到二維碼，使用真機調試就沒問題。感謝網友“落葉”的提醒，模擬器選iphone5s及以上裝置也是可以檢測到的。）

2，從相簿中選擇圖片讀取二維碼

代碼如下

複製代碼

import UIKit   class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {           override func viewDidLoad() {         super.viewDidLoad()     }           //選取相簿     @IBAction func fromAlbum(sender: AnyObject) {         //判斷設定是否支援圖片庫         if UIImagePickerController.isSourceTypeAvailable(.PhotoLibrary){             //初始化圖片控制器             let picker = UIImagePickerController()             //設定代理             picker.delegate = self             //指定圖片控制器類型             picker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary             //彈出控制器，顯示介面             self.presentViewController(picker, animated: true, completion: {                 () -> Void in             })         }else{             print("讀取相簿錯誤")         }     }           //選擇圖片成功後代理     func imagePickerController(picker: UIImagePickerController,         didFinishPickingMediaWithInfo info: [String : AnyObject]) {           //擷取選擇的原圖         let image = info[UIImagePickerControllerOriginalImage] as! UIImage                  //二維碼讀取         let ciImage:CIImage=CIImage(image:image)!         let context = CIContext(options: nil)         let detector:CIDetector=CIDetector(ofType: CIDetectorTypeQRCode,             context: context, options: [CIDetectorAccuracy:CIDetectorAccuracyHigh])         let features=detector.featuresInImage(ciImage)         print("掃描到二維碼個數：\(features.count)")         //遍曆所有的二維碼，並框出         for feature in features as! [CIQRCodeFeature] {             print(feature.messageString)         }                   //圖片控制器退出         picker.dismissViewControllerAnimated(true, completion: {             () -> Void in         })     }           override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }

3，使用網路攝影機掃描讀取二維碼
（1）掃描主要使用的是 AVFoundation，用起來方便簡單
（2）通過 AVCaptureMetadataOutput 的 rectOfInterest 屬性，可以設定探測探測地區。同時給這個探測地區添加個方框，只有在框中的二維碼才會被掃描到。

效果圖如下：

代碼如下

 

代碼如下

複製代碼

import UIKit import AVFoundation   class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate, UIAlertViewDelegate{       var scanRectView:UIView!     var device:AVCaptureDevice!     var input:AVCaptureDeviceInput!     var output:AVCaptureMetadataOutput!     var session:AVCaptureSession!     var preview:AVCaptureVideoPreviewLayer!           override func viewDidLoad() {         super.viewDidLoad()     }           //通過網路攝影機掃描     @IBAction func fromCamera(sender: AnyObject) {         do{             self.device = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)                           self.input = try AVCaptureDeviceInput(device: device)                           self.output = AVCaptureMetadataOutput()             output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())                           self.session = AVCaptureSession()             if UIScreen.mainScreen().bounds.size.height<500 {                 self.session.sessionPreset = AVCaptureSessionPreset640x480             }else{                 self.session.sessionPreset = AVCaptureSessionPresetHigh             }                           self.session.addInput(self.input)             self.session.addOutput(self.output)                           self.output.metadataObjectTypes = [AVMetadataObjectTypeQRCode]                           //計算中間可探測地區             let windowSize:CGSize = UIScreen.mainScreen().bounds.size;             let scanSize:CGSize = CGSizeMake(windowSize.width*3/4,                 windowSize.width*3/4);             var scanRect:CGRect = CGRectMake((windowSize.width-scanSize.width)/2,                 (windowSize.height-scanSize.height)/2, scanSize.width, scanSize.height);             //計算rectOfInterest 注意x,y交換位置             scanRect = CGRectMake(scanRect.origin.y/windowSize.height,                 scanRect.origin.x/windowSize.width,                 scanRect.size.height/windowSize.height,                 scanRect.size.width/windowSize.width);             //設定可探測地區             self.output.rectOfInterest = scanRect                           self.preview = AVCaptureVideoPreviewLayer(session:self.session)             self.preview.videoGravity = AVLayerVideoGravityResizeAspectFill             self.preview.frame = UIScreen.mainScreen().bounds             self.view.layer.insertSublayer(self.preview, atIndex:0)                           //添加中間的探測地區綠框             self.scanRectView = UIView();             self.view.addSubview(self.scanRectView)             self.scanRectView.frame = CGRectMake(0, 0, scanSize.width, scanSize.height);             self.scanRectView.center = CGPointMake(                 CGRectGetMidX(UIScreen.mainScreen().bounds),                 CGRectGetMidY(UIScreen.mainScreen().bounds));             self.scanRectView.layer.borderColor = UIColor.greenColor().CGColor             self.scanRectView.layer.borderWidth = 1;                           //開始捕獲             self.session.startRunning()         }catch _ as NSError{             //列印錯誤訊息             let errorAlert = UIAlertView(title: "提醒",                 message: "請在iPhone的\"設定-隱私-相機\"選項中,允許本程式訪問您的相機",                 delegate: self,                 cancelButtonTitle: "確定")             errorAlert.show()         }     }           //網路攝影機捕獲     func captureOutput(captureOutput: AVCaptureOutput!,         didOutputMetadataObjects metadataObjects: [AnyObject]!,         fromConnection connection: AVCaptureConnection!) {                   var stringValue:String?         if metadataObjects.count > 0 {             let metadataObject = metadataObjects[0] as! AVMetadataMachineReadableCodeObject             stringValue = metadataObject.stringValue                           if stringValue != nil{                 self.session.stopRunning()             }         }         self.session.stopRunning()         //輸出結果         let alertView = UIAlertView(title: "二維碼", message: stringValue,             delegate: self, cancelButtonTitle: "確定")         alertView.show()     }           //訊息框確認後消失     func alertView(alertView: UIAlertView, willDismissWithButtonIndex buttonIndex: Int) {          //繼續掃描          self.session.startRunning()     }           override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }