[摘要]本文是對iOS 二維碼的生成和掃描的講解，對學習IOS蘋果軟件開發有所幫助,與大家分享。

屬性

@property (strong,nonatomic)AVCaptureDevice * device;
@property (strong,nonatomic)AVCaptureDeviceInput * input;
@property (strong,nonatomic)AVCaptureMetadataOutput * output;
@property (strong,nonatomic)AVCaptureSession * session;
@property (strong,nonatomic)AVCaptureVideoPreviewLayer * layer;

@property (nonatomic, strong)UIImageView *imageView;

二維碼的生成

 // 1.創建過濾器
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

    // 2.恢復默認
    [filter setDefaults];

    // 3.給過濾器添加數據(正則表達式/賬號和密碼)
    NSString *dataString = @"http://www.520it.com";
    NSData *data = [dataString dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:data forKeyPath:@"inputMessage"];

    // 4.獲取輸出的二維碼
    CIImage *outputImage = [filter outputImage];

    //因為生成的二維碼模糊，所以通過createNonInterpolatedUIImageFormCIImage:outputImage來獲得高清的二維碼圖片

    // 5.顯示二維碼
    self.imageView.image = [self createNonInterpolatedUIImageFormCIImage:outputImage withSize:200];

* createNonInterpolatedUIImageFormCIImage:outputImage方法的實現

/**
 *  根據CIImage生成指定大小的UIImage
 *
 *  @param image CIImage
 *  @param size  圖片寬度
 */
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size
{
    CGRect extent = CGRectIntegral(image.extent);
    CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

    // 1.創建bitmap;
    size_t width = CGRectGetWidth(extent) * scale;
    size_t height = CGRectGetHeight(extent) * scale;
    CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
    CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    CGContextDrawImage(bitmapRef, extent, bitmapImage);

    // 2.保存bitmap到圖片
    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    return [UIImage imageWithCGImage:scaledImage];
}

二維碼的掃描

 // 1.創建捕捉會話
    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    self.session = session;

    // 2.添加輸入設備(數據從攝像頭輸入)
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
    [session addInput:input];

    // 3.添加輸出數據(示例對象-->類對象-->元類對象-->根元類對象)
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [session addOutput:output];

    // 3.1.設置輸入元數據的類型(類型是二維碼數據)
    [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

    // 4.添加掃描圖層
    AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];
    layer.frame = self.view.bounds;
    [self.view.layer addSublayer:layer];
    self.layer = layer;

    // 5.開始掃描
    [session startRunning];

*掃描到結果後會調用的方法

// 當掃描到數據時就會執行該方法
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    if (metadataObjects.count > 0) {
        //獲得掃描數據，最後一個時最新掃描的數據
        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];
        NSLog(@"%@", object.stringValue);

        // 停止掃描
        [self.session stopRunning];

        // 將預覽圖層移除
        [self.layer removeFromSuperlayer];
    } else {
        NSLog(@"沒有掃描到數據");
    }
}