iOS：原生二維碼掃描

作iOS的二維碼掃描，有兩個第三方庫能夠選擇，ZBar和ZXing。今天要介紹的是iOS7.0後AVFoundation框架提供的原生二維碼掃描。

首先須要添加AVFoundation.framework框架到你工程中build phase的"Link Binary With Libraries"之下，而後就能夠開始了。

1、作好準備工做，搭建UI

UI效果如圖

IBOutlet、IBAction以下：

@property (weak, nonatomic) IBOutlet UIView *viewPreview; @property (weak, nonatomic) IBOutlet UILabel *lblStatus; @property (weak, nonatomic) IBOutlet UIButton *startBtn; - (IBAction)startStopReading:(id)sender;

接下來就都是代碼的事情了

2、控制器ViewController.h

首先導入AVFoundation框架

#import <AVFoundation/AVFoundation.h>

而後控制器實現 AVCaptureMetadataOutputObjectsDelegate協議

@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>

總體property以下：

@property (strong, nonatomic) UIView *boxView; @property (nonatomic) BOOL isReading; @property (strong, nonatomic) CALayer *scanLayer; -(BOOL)startReading; -(void)stopReading; //捕捉會話 @property (nonatomic, strong) AVCaptureSession *captureSession; //展現layer @property (nonatomic, strong) AVCaptureVideoPreviewLayer *videoPreviewLayer;

而後在ViewDidLoad方法中初始化

- (void)viewDidLoad {
    [super viewDidLoad];

    _captureSession = nil; _isReading = NO; }

接下來實現startReading方法（這可就是重點咯）

- (BOOL)startReading {
  NSError *error;
 //1.初始化捕捉設備（AVCaptureDevice），類型爲AVMediaTypeVideo  AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];  //2.用captureDevice建立輸入流  AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];  if (!input) {   NSLog(@"%@", [error localizedDescription]);   return NO;  }  //3.建立媒體數據輸出流  AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];  //4.實例化捕捉會話  _captureSession = [[AVCaptureSession alloc] init];  //4.1.將輸入流添加到會話  [_captureSession addInput:input];  //4.2.將媒體輸出流添加到會話中  [_captureSession addOutput:captureMetadataOutput];  //5.建立串行隊列，並加媒體輸出流添加到隊列當中  dispatch_queue_t dispatchQueue;  dispatchQueue = dispatch_queue_create("myQueue", NULL);  //5.1.設置代理  [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];  //5.2.設置輸出媒體數據類型爲QRCode  [captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];  //6.實例化預覽圖層  _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];  //7.設置預覽圖層填充方式  [_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];  //8.設置圖層的frame  [_videoPreviewLayer setFrame:_viewPreview.layer.bounds];  //9.將圖層添加到預覽view的圖層上  [_viewPreview.layer addSublayer:_videoPreviewLayer];  //10.設置掃描範圍  captureMetadataOutput.rectOfInterest = CGRectMake(0.2f, 0.2f, 0.8f, 0.8f);  //10.1.掃描框  _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.掃描線  _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.開始掃描  [_captureSession startRunning];  return YES; } 

實現AVCaptureMetadataOutputObjectsDelegate協議方法

#pragma mark - AVCaptureMetadataOutputObjectsDelegate - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {  //判斷是否有數據  if (metadataObjects != nil && [metadataObjects count] > 0) {   AVMetadataMachineReadableCodeObject *metadataObj = [metadataObjects objectAtIndex:0];   //判斷回傳的數據類型   if ([[metadataObj type] isEqualToString:AVMetadataObjectTypeQRCode]) {    [_lblStatus performSelectorOnMainThread:@selector(setText:) withObject:[metadataObj stringValue] waitUntilDone:NO];    [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];    _isReading = NO;   }  } } 

實現計時器方法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;   }];  } } 

實現開始和中止方法

- (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

示例源碼地址： https://github.com/WuKongCoo1/QRCodeReader