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 
    

然后控制器实现 AVCaptureMetadataOutputObjectsDelegate协议

@interface ViewController ()
    

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：