1，直接讀取圖片中的二維碼 使用?CIDetector?可以很方便的檢測并讀取二維碼。下面是一個從?UIImage?中讀取二維碼的樣例，我們要把圖片上所有的二維碼信息都打印出來。

代碼如下：

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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)") ????????//遍歷所有的二維碼，并框出 ????????for?feature?in?features?as! [CIQRCodeFeature] { ????????????print(feature.messageString) ????????} ????} ????override?func?didReceiveMemoryWarning() { ????????super.didReceiveMemoryWarning() ????} }

控制臺輸出如下： 掃描到二維碼個數：2
http://www.hangge.com
http://www.hangge.com 可以看到兩個二維碼都成功的讀取到了。
（注：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及以上設備也是可以檢測到的。）?

2，從相冊中選擇圖片讀取二維碼

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import?UIKit class?ViewController:?UIViewController,?UIImagePickerControllerDelegate, UINavigationControllerDelegate?{ ????? ????override?func?viewDidLoad() { ????????super.viewDidLoad() ????} ????? ????//選取相冊 ????@IBAction?func?fromAlbum(sender:?AnyObject) { ????????//判斷設置是否支持圖片庫 ????????if?UIImagePickerController.isSourceTypeAvailable(.PhotoLibrary){ ????????????//初始化圖片控制器 ????????????let?picker =?UIImagePickerController() ????????????//設置代理 ????????????picker.delegate =?self ????????????//指定圖片控制器類型 ????????????picker.sourceType =?UIImagePickerControllerSourceType.PhotoLibrary ????????????//彈出控制器，顯示界面 ????????????self.presentViewController(picker, animated:?true, completion: { ????????????????() ->?Void?in ????????????}) ????????}else{ ????????????print("讀取相冊錯誤") ????????} ????} ????? ????//選擇圖片成功后代理 ????func?imagePickerController(picker:?UIImagePickerController, ????????didFinishPickingMediaWithInfo info: [String?:?AnyObject]) { ????????//獲取選擇的原圖 ????????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)") ????????//遍歷所有的二維碼，并框出 ????????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，使用攝像頭掃描讀取二維碼
（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，可以設置探測探測區域。同時給這個探測區域添加個方框，只有在框中的二維碼才會被掃描到。

效果圖如下：
代碼如下：

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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() ????} ????? ????//通過攝像頭掃描 ????@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] ????????????? ????????????//計算中間可探測區域 ????????????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); ????????????//設置可探測區域 ????????????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) ????????????? ????????????//添加中間的探測區域綠框 ????????????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{ ????????????//打印錯誤消息 ????????????let?errorAlert =?UIAlertView(title:?"提醒", ????????????????message:?"請在iPhone的\"設置-隱私-相機\"選項中,允許本程序訪問您的相機", ????????????????delegate:?self, ????????????????cancelButtonTitle:?"確定") ????????????errorAlert.show() ????????} ????} ????? ????//攝像頭捕獲 ????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() ????} ????? ????//消息框確認后消失 ????func?alertView(alertView:?UIAlertView, willDismissWithButtonIndex buttonIndex:?Int) { ?????????//繼續掃描 ?????????self.session.startRunning() ????} ????? ????override?func?didReceiveMemoryWarning() { ????????super.didReceiveMemoryWarning() ????} }

原文出自： www.hangge.com ??轉載請保留原文鏈接： http://www.hangge.com/blog/cache/detail_915.html

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