ios原生二维码扫描

做iOS的二维码扫描，有两个第三方库可以选择，ZBar和ZXing。今天要介绍的是iOS7.0后AVFoundation框架提供的原生二维码扫描。

首先需要添加AVFoundation.framework框架到你工程中build phase的"Link Binary With Libraries"之下，然后就可以开始了。

一、做好准备工作，搭建UI

UI效果如图

IBOutlet、IBAction如下：

@property(weak, nonatomic) IBOutlet UIView *viewPreview;

@property(weak, nonatomic) IBOutlet UILabel *lblStatus;

@property(weak, nonatomic) IBOutlet UIButton *startBtn;

- (IBAction)startStopReading:(id)sender;

接下来就都是代码的事情了

二、控制器ViewController.h

首先导入AVFoundation框架

1#import<AVFoundation/AVFoundation.h>

然后控制器实现 AVCaptureMetadataOutputObjectsDelegate协议

1@interfaceViewController ()<AVCaptureMetadataOutputObjectsDelegate>

整体property如下：

@property(strong, nonatomic) UIView *boxView;

@property(nonatomic) BOOL isReading;

@property(strong, nonatomic) CALayer *scanLayer;

-(BOOL)startReading;

-(void)stopReading;

//捕捉会话

1@property (nonatomic, strong) AVCaptureSession *captureSession;

//展示layer

1@property(nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;

然后在ViewDidLoad方法中初始化

- (void)viewDidLoad {

  [superviewDidLoad];

  _captureSession = nil;

   _isReading = NO;

}

接下来实现startReading方法（这可就是重点咯）

- (BOOL)startReading {

 NSError *error;

 //1.初始化捕捉设备（AVCaptureDevice），类型为AVMediaTypeVideo

 AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

 //2.用captureDevice创建输入流

 AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

 if(!input) {

  NSLog(@"%@", [error localizedDescription]);

  returnNO;

 }

 //3.创建媒体数据输出流

 AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];

 //4.实例化捕捉会话

 _captureSession = [[AVCaptureSession alloc] init];

 //4.1.将输入流添加到会话

 [_captureSession addInput:input];

 //4.2.将媒体输出流添加到会话中

 [_captureSession addOutput:captureMetadataOutput];

 //5.创建串行队列，并加媒体输出流添加到队列当中

 dispatch_queue_t dispatchQueue;

 dispatchQueue = dispatch_queue_create("myQueue", NULL);

 //5.1.设置代理

 [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];

 //5.2.设置输出媒体数据类型为QRCode

 [captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];

 //6.实例化预览图层

 _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];

 //7.设置预览图层填充方式

 [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

 //8.设置图层的frame

 [_videoPreviewLayer setFrame:_viewPreview.layer.bounds];

 //9.将图层添加到预览view的图层上

 [_viewPreview.layer addSublayer:_videoPreviewLayer];

 //10.设置扫描范围

 captureMetadataOutput.rectOfInterest = CGRectMake(0.2f, 0.2f, 0.8f, 0.8f);

 //10.1.扫描框

 _boxView = [[UIView alloc] initWithFrame:CGRectMake(_viewPreview.bounds.size.width * 0.2f, _viewPreview.bounds.size.height * 0.2f, _viewPreview.bounds.size.width - _viewPreview.bounds.size.width * 0.4f, _viewPreview.bounds.size.height - _viewPreview.bounds.size.height * 0.4f)];

 _boxView.layer.borderColor = [UIColor greenColor].CGColor;

 _boxView.layer.borderWidth = 1.0f;

 [_viewPreview addSubview:_boxView];

 //10.2.扫描线

 _scanLayer = [[CALayer alloc] init];

 _scanLayer.frame = CGRectMake(0, 0, _boxView.bounds.size.width, 1);

 _scanLayer.backgroundColor = [UIColor brownColor].CGColor;

 [_boxView.layer addSublayer:_scanLayer];

 NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.2f target:self selector:@selector(moveScanLayer:) userInfo:nil repeats:YES];

 [timer fire];

 //10.开始扫描

 [_captureSession startRunning];

 returnYES;

}

实现AVCaptureMetadataOutputObjectsDelegate协议方法

#pragma mark - AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection

{

 //判断是否有数据

 if(metadataObjects != nil && [metadataObjects count] > 0) {

  AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];

  //判断回传的数据类型

  if([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {

   [_lblStatus performSelectorOnMainThread:@selector(setText:) withObject:[metadataObj stringValue] waitUntilDone:NO];

   [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];

   _isReading = NO;

  }

 }

}

实现计时器方法moveScanLayer:(NSTimer *)timer

- (void)moveScanLayer:(NSTimer *)timer

{

 CGRect frame = _scanLayer.frame;

 if(_boxView.frame.size.height < _scanLayer.frame.origin.y) {

  frame.origin.y = 0;

  _scanLayer.frame = frame;

 }else{

  frame.origin.y += 5;

  [UIView animateWithDuration:0.1animations:^{

   _scanLayer.frame = frame;

  }];

 }

}

实现开始和停止方法

- (IBAction)startStopReading:(id)sender {

  if(!_isReading) {

   if([self startReading]) {

    [_startBtn setTitle:@"Stop"forState:UIControlStateNormal];

    [_lblStatus setText:@"Scanning for QR Code"];

   }

  }

  else{

   [self stopReading];

   [_startBtn setTitle:@"Start!"forState:UIControlStateNormal];

  }

  _isReading = !_isReading;

}

-(void)stopReading{

 [_captureSession stopRunning];

 _captureSession = nil;

 [_scanLayer removeFromSuperlayer];

 [_videoPreviewLayer removeFromSuperlayer];

}

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