Swift - 二维码QRCode的读取（从图片读取 ，或通过摄像头扫描）

1，直接读取图片中的二维码

使用 CIDetector 可以很方便的检测并读取二维码。下面是一个从 UIImage 中读取二维码的样例，我们要把图片上所有的二维码信息都打印出来。

代码如下：

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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("扫描到二维码个数：\(features.count)")

        //遍历所有的二维码，并框出

        for feature in features as! [CIQRCodeFeature] {

            print(feature.messageString)

        }

    }

 

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}

2，从相册中选择图片读取二维码

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import UIKit

 

class ViewController: UIViewController, UIImagePickerControllerDelegate,

UINavigationControllerDelegate {

     

    override func viewDidLoad() {

        super.viewDidLoad()

    }

     

    //选取相册

    @IBAction func fromAlbum(sender: AnyObject) {

        //判断设置是否支持图片库

        if UIImagePickerController.isSourceTypeAvailable(.PhotoLibrary){

            //初始化图片控制器

            let picker = UIImagePickerController()

            //设置代理

            picker.delegate = self

            //指定图片控制器类型

            picker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary

            //弹出控制器，显示界面

            self.presentViewController(picker, animated: true, completion: {

                () -> Void in

            })

        }else{

            print("读取相册错误")

        }

    }

     

    //选择图片成功后代理

    func imagePickerController(picker: UIImagePickerController,

        didFinishPickingMediaWithInfo info: [String : AnyObject]) {

 

        //获取选择的原图

        let image = info[UIImagePickerControllerOriginalImage] as! UIImage

        

        //二维码读取

        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("扫描到二维码个数：\(features.count)")

        //遍历所有的二维码，并框出

        for feature in features as! [CIQRCodeFeature] {

            print(feature.messageString)

        }

         

        //图片控制器退出

        picker.dismissViewControllerAnimated(true, completion: {

            () -> Void in

        })

    }

     

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}

3，使用摄像头扫描读取二维码
（1）扫描主要使用的是 AVFoundation，用起来方便简单
（2）通过 AVCaptureMetadataOutput 的 rectOfInterest 属性，可以设置探测探测区域。同时给这个探测区域添加个方框，只有在框中的二维码才会被扫描到。

代码如下：

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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()

    }

     

    //通过摄像头扫描

    @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]

             

            //计算中间可探测区域

            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);

            //计算rectOfInterest 注意x,y交换位置

            scanRect = CGRectMake(scanRect.origin.y/windowSize.height,

                scanRect.origin.x/windowSize.width,

                scanRect.size.height/windowSize.height,

                scanRect.size.width/windowSize.width);

            //设置可探测区域

            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)

             

            //添加中间的探测区域绿框

            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;

             

            //开始捕获

            self.session.startRunning()

        }catch _ as NSError{

            //打印错误消息

            let errorAlert = UIAlertView(title: "提醒",

                message: "请在iPhone的\"设置-隐私-相机\"选项中,允许本程序访问您的相机",

                delegate: self,

                cancelButtonTitle: "确定")

            errorAlert.show()

        }

    }

     

    //摄像头捕获

    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()

        //输出结果

        let alertView = UIAlertView(title: "二维码", message: stringValue,

            delegate: self, cancelButtonTitle: "确定")

        alertView.show()

    }

     

    //消息框确认后消失

    func alertView(alertView: UIAlertView, willDismissWithButtonIndex buttonIndex: Int) {

         //继续扫描

         self.session.startRunning()

    }

     

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

    }

}