iOS开发-QRCode-二维码识别与生成
jopen
8年前
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 .
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
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 < width; ++i) { for(int j = 0; j < width; ++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 && i<=6 && j>=0 && j<=6) || (i>=0 && i<=6 && j>=width-7-1 && j<=width-1) || (i>=width-7-1 && i<=width-1 && j>=0 && j<=6)) { CGContextAddRect(ctx, rectDraw); }else { CGContextAddEllipseInRect(ctx, rectDraw); } break; default: break; } } } ++data; } } CGContextFillPath(ctx); }在textField输入，生成下图
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。
#pragma mark-> 长按识别二维码 -(void)dealLongPress:(UIGestureRecognizer*)gesture{ if(gesture.state==UIGestureRecognizerStateBegan){ _timer.fireDate=[NSDate distantFuture]; UIImageView*tempImageView=(UIImageView*)gesture.view; if(tempImageView.image){ //1. 初始化扫描仪，设置设别类型和识别质量 CIDetector*detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{ CIDetectorAccuracy : CIDetectorAccuracyHigh }]; //2. 扫描获取的特征组 NSArray *features = [detector featuresInImage:[CIImage imageWithCGImage:tempImageView.image.CGImage]]; //3. 获取扫描结果 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:@"扫描结果" message:@"您还没有生成二维码" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil]; [alertView show]; } }else if (gesture.state==UIGestureRecognizerStateEnded){ _timer.fireDate=[NSDate distantPast]; } }我们用刚才生成的二维码进行长按识别，效果如下
结语
本文demo下载地址请点这里 Demo ,
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。
文章若有问题请给予指正，感谢。
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