QRCode - 二维码识别与生成

淩亂°似流年 2022-03-27 13:26 452阅读 0赞

> 来源：Yi'mouleng（@丶伊眸冷）

> 链接：http://t.cn/R40WxcM

**前言**

有关二维码的介绍，我这里不做过多说明， 可以直接去基维百科查看，附上链接QR code（https://en.wikipedia.org/wiki/QR\_code）.

IOS7之前，开发者进行扫码编程时，一般会借助第三方库。常用的是ZBarSDKa和ZXingObjC，IOS7之后，系统的AVMetadataObject类中，为我们提供了解析二维码的接口。经过测试，使用原生API扫描和处理的效率非常高，远远高于第三方库。

**扫描**

官方提供的接口非常简单，直接看代码，主要使用的是AVFoundation。

> @interface ViewController ()AVCaptureMetadataOutputObjectsDelegate>//用于处理采集信息的代理
> 
> \{
> 
>     AVCaptureSession \* session;//输入输出的中间桥梁
> 
> \}
> 
> @end
> 
> @implementation ViewController
> 
>  
> 
> \- (void)viewDidLoad \{
> 
>     \[super viewDidLoad\];
> 
>     // Do any additional setup after loading the view, typically from a nib.
> 
>     //获取摄像设备
> 
>     AVCaptureDevice \* device = \[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo\];
> 
>     //创建输入流
> 
>     AVCaptureDeviceInput \* input = \[AVCaptureDeviceInput deviceInputWithDevice:device error:nil\];
> 
>     if (!input) return;
> 
>     //创建输出流
> 
>     AVCaptureMetadataOutput \* output = \[\[AVCaptureMetadataOutput alloc\]init\];
> 
>     //设置代理 在主线程里刷新
> 
>     \[output setMetadataObjectsDelegate:self queue:dispatch\_get\_main\_queue()\];
> 
>     //设置有效扫描区域
> 
>     CGRect scanCrop=\[self getScanCrop:\_scanWindow.bounds readerViewBounds:self.view.frame\];
> 
>      output.rectOfInterest = scanCrop;
> 
>     //初始化链接对象
> 
>     \_session = \[\[AVCaptureSession alloc\]init\];
> 
>     //高质量采集率
> 
>     \[\_session setSessionPreset:AVCaptureSessionPresetHigh\];
> 
>     
> 
>     \[\_session addInput:input\];
> 
>     \[\_session addOutput:output\];
> 
>     //设置扫码支持的编码格式(如下设置条形码和二维码兼容)
> 
>     output.metadataObjectTypes=@\[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code\];
> 
>     
> 
>     AVCaptureVideoPreviewLayer \* layer = \[AVCaptureVideoPreviewLayer layerWithSession:\_session\];
> 
>     layer.videoGravity=AVLayerVideoGravityResizeAspectFill;
> 
>     layer.frame=self.view.layer.bounds;
> 
>     \[self.view.layer insertSublayer:layer atIndex:0\];
> 
>     //开始捕获
> 
>     \[\_session startRunning\];
> 
> \}
> 
>  
> 
> \-(void)captureOutput:(AVCaptureOutput \*)captureOutput didOutputMetadataObjects:(NSArray \*)metadataObjects fromConnection:(AVCaptureConnection \*)connection\{
> 
>     if (metadataObjects.count>0) \{
> 
>         //\[session stopRunning\];
> 
>         AVMetadataMachineReadableCodeObject \* metadataObject = \[metadataObjects objectAtIndex : 0 \];
> 
>         //输出扫描字符串
> 
>         NSLog(@"%@",metadataObject.stringValue);
> 
>     \}
> 
> \}

一些初始化的代码加上实现代理方法便完成了二维码扫描的工作，这里我们需要注意的是， 在二维码扫描的时候， 我们一般都会在屏幕中间放一个方框，用来显示二维码扫描的大小区间，这里我们在个AVCaptureMetadataOutput类中有一个rectOfInterest属性，它的作用就是设置扫描范围。

> 这个CGRect参数和普通的Rect范围不太一样，它的四个值的范围都是0-1，表示比例。  
> rectOfInterest都是按照横屏来计算的 所以当竖屏的情况下 x轴和y轴要交换一下。  
> 宽度和高度设置的情况也是类似。

我们在上面设置有效扫描区域的方法如下

> \#pragma mark-> 获取扫描区域的比例关系
> 
> \-(CGRect)getScanCrop:(CGRect)rect readerViewBounds:(CGRect)readerViewBounds
> 
> \{
> 
>     
> 
>     CGFloat x,y,width,height;
> 
>     
> 
>     x = (CGRectGetHeight(readerViewBounds)-CGRectGetHeight(rect))/2/CGRectGetHeight(readerViewBounds);
> 
>     y = (CGRectGetWidth(readerViewBounds)-CGRectGetWidth(rect))/2/CGRectGetWidth(readerViewBounds);
> 
>     width = CGRectGetHeight(rect)/CGRectGetHeight(readerViewBounds);
> 
>     height = CGRectGetWidth(rect)/CGRectGetWidth(readerViewBounds);
> 
>     
> 
>     return CGRectMake(x, y, width, height);
> 
>     
> 
> \}

**读取**

读取主要用到CoreImage 不过要强调的是读取二维码的功能只有在iOS8之后才支持，我们需要在相册中调用一个二维码，将其读取，代码如下

> \#pragma mark-> 我的相册
> 
> \-(void)myAlbum\{
> 
>     
> 
>     NSLog(@"我的相册");
> 
>     if(\[UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary\])\{
> 
>         //1.初始化相册拾取器
> 
>         UIImagePickerController \*controller = \[\[UIImagePickerController alloc\] init\];
> 
>         //2.设置代理
> 
>         controller.delegate = self;
> 
>         //3.设置资源：
> 
>         /\*\*
> 
>          UIImagePickerControllerSourceTypePhotoLibrary,相册
> 
>          UIImagePickerControllerSourceTypeCamera,相机
> 
>          UIImagePickerControllerSourceTypeSavedPhotosAlbum,照片库
> 
>          \*/
> 
>         controller.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
> 
>         //4.随便给他一个转场动画
> 
>         controller.modalTransitionStyle=UIModalTransitionStyleFlipHorizontal;
> 
>         \[self presentViewController:controller animated:YES completion:NULL\];
> 
>         
> 
>     \}else\{
> 
>         
> 
>         UIAlertView \* alert = \[\[UIAlertView alloc\]initWithTitle:@"提示" message:@"设备不支持访问相册，请在设置->隐私->照片中进行设置！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil\];
> 
>         \[alert show\];
> 
>     \}
> 
>     
> 
> \}

完成相册代理， 我们在代理中添加读取二维码方法

> \#pragma mark-> imagePickerController delegate
> 
> \- (void)imagePickerController:(UIImagePickerController \*)picker didFinishPickingMediaWithInfo:(NSDictionary \*)info
> 
> \{
> 
>     //1.获取选择的图片
> 
>     UIImage \*image = info\[UIImagePickerControllerOriginalImage\];
> 
>     //2.初始化一个监测器
> 
>     CIDetector\*detector = \[CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@\{  CIDetectorAccuracy : CIDetectorAccuracyHigh \}\];
> 
>     
> 
>     \[picker dismissViewControllerAnimated:YES completion:^\{
> 
>         //监测到的结果数组
> 
>         NSArray \*features = \[detector featuresInImage:\[CIImage imageWithCGImage:image.CGImage\]\];
> 
>         if (features.count >=1) \{
> 
>             /\*\*结果对象 \*/
> 
>             CIQRCodeFeature \*feature = \[features objectAtIndex:0\];
> 
>             NSString \*scannedResult = feature.messageString;
> 
>             UIAlertView \* alertView = \[\[UIAlertView alloc\]initWithTitle:@"扫描结果" message:scannedResult delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil\];
> 
>             \[alertView show\];
> 
>           
> 
>         \}
> 
>         else\{
> 
>             UIAlertView \* alertView = \[\[UIAlertView alloc\]initWithTitle:@"提示" message:@"该图片没有包含一个二维码！" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil\];
> 
>             \[alertView show\];
> 
>             
> 
>         \}
> 
>         
> 
>   
> 
>     \}\];
> 
>     
> 
>     
> 
> \}

因为没用真机，所以这里没有给出太多的截图， 用模拟器读取自带图片，结果如下

![708266-20161024082910875-2076700226.jpg][]

**生成**

生成二维码，其实也是用到CoreImage，但是步骤繁琐一些，代码如下

> \#pragma mark-> 二维码生成
> 
> \-(void)create\{
> 
>     
> 
>     UIImage \*image=\[UIImage imageNamed:@"6824500\_006\_thumb.jpg"\];
> 
>     NSString\*tempStr;
> 
>     if(self.textField.text.length==0)\{
> 
>         
> 
>         tempStr=@"ddddddddd";
> 
>         
> 
>     \}else\{
> 
>         
> 
>         tempStr=self.textField.text;
> 
>         
> 
>     \}
> 
>     UIImage\*tempImage=\[QRCodeGenerator qrImageForString:tempStr imageSize:360 Topimg:image withColor:RandomColor\];
> 
>     
> 
>     \_outImageView.image=tempImage;
> 
>     
> 
> \}
> 
> \+(UIImage\*)qrImageForString:(NSString \*)string imageSize:(CGFloat)size Topimg:(UIImage \*)topimg withColor:(UIColor\*)color\{
> 
>     
> 
>     if (!\[string length\]) \{
> 
>         return nil;
> 
>     \}
> 
>     
> 
>     QRcode \*code = QRcode\_encodeString(\[string UTF8String\], 0, QR\_ECLEVEL\_L, QR\_MODE\_8, 1);
> 
>     if (!code) \{
> 
>         return nil;
> 
>     \}
> 
>     
> 
>     // create context
> 
>     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
> 
>     CGContextRef ctx = CGBitmapContextCreate(0, size, size, 8, size \* 4, colorSpace, kCGImageAlphaPremultipliedLast);
> 
>     
> 
>     CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(0, -size);
> 
>     CGAffineTransform scaleTransform = CGAffineTransformMakeScale(1, -1);
> 
>     CGContextConcatCTM(ctx, CGAffineTransformConcat(translateTransform, scaleTransform));
> 
>     
> 
>     // draw QR on this context
> 
>     \[QRCodeGenerator drawQRCode:code context:ctx size:size withPointType:0 withPositionType:0 withColor:color\];
> 
>     
> 
>     // get image
> 
>     CGImageRef qrCGImage = CGBitmapContextCreateImage(ctx);
> 
>     UIImage \* qrImage = \[UIImage imageWithCGImage:qrCGImage\];
> 
>     
> 
>     if(topimg)
> 
>     \{
> 
>         UIGraphicsBeginImageContext(qrImage.size);
> 
>         
> 
>         //Draw image2
> 
>         \[qrImage drawInRect:CGRectMake(0, 0, qrImage.size.width, qrImage.size.height)\];
> 
>         
> 
>         //Draw image1
> 
>         float r=qrImage.size.width\*35/240;
> 
>         \[topimg drawInRect:CGRectMake((qrImage.size.width-r)/2, (qrImage.size.height-r)/2 ,r, r)\];
> 
>  
> 
>         qrImage=UIGraphicsGetImageFromCurrentImageContext();
> 
>         
> 
>         UIGraphicsEndImageContext();
> 
>     \}
> 
>  
> 
>     // some releases
> 
>     CGContextRelease(ctx);
> 
>     CGImageRelease(qrCGImage);
> 
>     CGColorSpaceRelease(colorSpace);
> 
>     QRcode\_free(code);
> 
>     
> 
>     return qrImage;
> 
>       
> 
> \}
> 
> \+ (void)drawQRCode:(QRcode \*)code context:(CGContextRef)ctx size:(CGFloat)size withPointType:(QRPointType)pointType withPositionType:(QRPositionType)positionType withColor:(UIColor \*)color \{
> 
> unsigned char \*data = 0;
> 
> int width;
> 
> data = code->data;
> 
> width = code->width;
> 
> float zoom = (double)size / (code->width + 2.0 \* qr\_margin);
> 
> CGRect rectDraw = CGRectMake(0, 0, zoom, zoom);
> 
>     
> 
> // draw
> 
>     const CGFloat \*components;
> 
>     if (color) \{
> 
>         components = CGColorGetComponents(color.CGColor);
> 
>     \}else \{
> 
>         components = CGColorGetComponents(\[UIColor blackColor\].CGColor);
> 
>     \}
> 
>     CGContextSetRGBFillColor(ctx, components\[0\], components\[1\], components\[2\], 1.0);
> 
>     NSLog(@"aad :%f  bbd :%f   ccd:%f",components\[0\],components\[1\],components\[2\]);
> 
>  
> 
> for(int i = 0; i
> 
> for(int j = 0; j
> 
> if(\*data & 1) \{
> 
> rectDraw.origin = CGPointMake((j + qr\_margin) \* zoom,(i + qr\_margin) \* zoom);
> 
>                 if (positionType == QRPositionNormal) \{
> 
>                     switch (pointType) \{
> 
>                         case QRPointRect:
> 
>                             CGContextAddRect(ctx, rectDraw);
> 
>                             break;
> 
>                         case QRPointRound:
> 
>                             CGContextAddEllipseInRect(ctx, rectDraw);
> 
>                             break;
> 
>                         default:
> 
>                             break;
> 
>                     \}
> 
>                 \}else if(positionType == QRPositionRound) \{
> 
>                     switch (pointType) \{
> 
>                         case QRPointRect:
> 
>                             CGContextAddRect(ctx, rectDraw);
> 
>                             break;
> 
>                         case QRPointRound:
> 
>                             if ((i>=0 && i6 && j>=0 && j6) || (i>=0 && i6 && j>=width-7-1 && j-1) || (i>=width-7-1 && i-1 && j>=0 && j6)) \{
> 
>                                 CGContextAddRect(ctx, rectDraw);
> 
>                             \}else \{
> 
>                                 CGContextAddEllipseInRect(ctx, rectDraw);
> 
>                             \}
> 
>                             break;
> 
>                         default:
> 
>                             break;
> 
>                     \}
> 
>                 \}
> 
> \}
> 
> \++data;
> 
> \}
> 
> \}
> 
> CGContextFillPath(ctx);
> 
> \}

在textField输入，生成下图

![708266-20161024082942218-459894891.jpg][]

**长按二维码识别**

这个功能有很多的地方在用， 最让人熟知的我想便是微信了，其实实现方法还是很简单的。

![708266-20161024083003953-804497594.jpg][]

我们用刚才生成的二维码进行长按识别，效果如下

![708266-20161024083028171-1169901110.jpg][]

**结语**

本文demo：https://github.com/yimouleng/GBAliScan

转自mokey1422所写的仿支付宝二维码。

系统原生的二维码扫描扫描识别速度，要比第三方好用得多，在没有特殊原因的情况下，比如7.0系统以下，我希望大家都能用系统原生的方法。

# iOS-原生二维码 #

http://www.jianshu.com/p/e15ca2799796

[708266-20161024082910875-2076700226.jpg]: /images/20220327/bd3c73c77c7a4754a9ab37046984022d.png
[708266-20161024082942218-459894891.jpg]: /images/20220327/a33343cddf20424fbf3bf1d2cc4ce408.png
[708266-20161024083003953-804497594.jpg]: /images/20220327/f782683dbac543b28e71713a2651db02.png
[708266-20161024083028171-1169901110.jpg]: /images/20220327/42e1187e9fb64f1fb9ef2d6e51bc193d.png