iOS开发-二维码识别与生成-QRCode

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.
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];

        }

    }];

}

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);
}

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];
    }

}

结语

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。