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

#import <AVFoundation/AVFoundation.h>

然后控制器实现 AVCaptureMetadataOutputObjectsDelegate协议

@interface ViewController ()<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 @property (nonatomic, strong) AVCaptureSession *captureSession; //展示layer @property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;

然后在ViewDidLoad方法中初始化

- (void)viewDidLoad {
    [super viewDidLoad];

    _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]);   return NO;  }  //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];  return YES; } 

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:0.1 animations:^{    _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]; } 

大功告成

示例源码地址： https://github.com/WuKongCoo1/QRCodeReader