二维码扫描（iOS原生二维码扫描）

一、关于二维码扫描的第三方库有很多：例如比较常用的两个

 1.ZBar SDK ZBar为我们提供了两种使用方式，一种是直接调用ZBar提供的ZBarReaderViewController打开一个扫描界面，另一种方式是使用ZBar提供的可以嵌在其他视图中的ZBarReaderView，实际项目中我们更可能会使用第二种方式，这可以让我们对界面做更多的定制,详细的百度查找相关文档来看。

 

 2.ZXing(Github镜像地址)是一个开源的条码生成和扫描库（开源协议为Apache2.0)。它不但支持众多的条码格式，而且有各种语言的实现版本，它支持的语言包括：Java、 C++、 C#、 Objective-C、ActionScript以及Ruby;首先去Google Code或Github将ZXing的代码下载下来，整个工程比较大，我们只需要其中涉及iOS的部分，所以最好做一些裁剪。简单来说，我们只需要保留cpp和iphone这2个文件夹，其余的全部删掉。

二、

1.本次介绍的是：iOS原生二维码扫描，利用iOS7自带的AVFoundation Framework 来实现二维码扫描

 关于AVFoundation：AVFoundation是一个很大基础库，用来创建基于时间的视听媒体，可以使用它来检查、创建、编辑或媒体文件，也可以输入流从设备和操作视频实时捕捉和回放。详细框架介绍见官网：About AV Foundation，本文只是介绍如果使用AVFoundation获取二维码。

 

 2.首先获取流媒体信息我们需要AVCaptureSession对象来管理输入流和输出流，AVCaptureVideoPreviewLayer对象来显示信息。

 

1>AVCaptureSession 管理输入(AVCaptureInput)和输出(AVCaptureOutput)流，包含开启和停止会话方法。

2>AVCaptureDeviceInput 是AVCaptureInput的子类,可以作为输入捕获会话，用AVCaptureDevice实例初始化。

3>AVCaptureDevice 代表了物理捕获设备如:摄像机。用于配置等底层硬件设置相机的自动对焦模式。

4>AVCaptureMetadataOutput 是AVCaptureOutput的子类，处理输出捕获会话。捕获的对象传递给一个委托实现

5>AVCaptureMetadataOutputObjectsDelegate协议。协议方法在指定的派发队列（dispatch queue）上执行。

6>AVCaptureVideoPreviewLayerCALayer的一个子类，显示捕获到的相机输出流。

/*
 步骤如下：
 1.导入AVFoundation框架，引入<AVFoundation/AVFoundation.h>
 2.设置一个用于显示扫描的view
 3.实例化AVCaptureSession、AVCaptureVideoPreviewLayer
 */

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>

@property (strong,nonatomic) UIView *viewPreview ;
@property (strong,nonatomic) UILabel *lblStatus ;
@property (strong,nonatomic) UIButton *startBtn ;

@property (strong,nonatomic) UIView *boxView ;
@property (nonatomic) BOOL isReading ;
@property (strong,nonatomic) CALayer *scanLayer;

-(BOOL)startReading;
-(void)stopReading ;

//捕捉会话
@property (strong,nonatomic) AVCaptureSession *captureSession;
//展示layer
@property (strong,nonatomic) AVCaptureVideoPreviewLayer *videoPreviewLayer;

@end


@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
//    self.view.backgroundColor = [UIColor whiteColor];
    self.captureSession = nil ;
    _isReading = NO ;
    [self initUI];
    
    
}

-(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];
//    AVCaptureOutput *outPut = [[AVCaptureOutput alloc] init];
    //4.实例化捕捉会话
    _captureSession = [[AVCaptureSession alloc] init];
    //4.1将输入流添加带会话
    [_captureSession addInput:input];
    //4.2将媒体输出流添加带会话中
    [_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];
    //
    //设置代理 刷新线程
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    //5.2.设置输出媒体数据类型为QRCode
//    [captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];
    if (captureMetadataOutput) {
        
        //设置扫码支持的编码格式
        NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:0];
        
        if ([captureMetadataOutput.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeQRCode]) {
            [array addObject:AVMetadataObjectTypeQRCode];
        }
        if ([captureMetadataOutput.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeEAN13Code]) {
            [array addObject:AVMetadataObjectTypeEAN13Code];
        }
        if ([captureMetadataOutput.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeEAN8Code]) {
            [array addObject:AVMetadataObjectTypeEAN8Code];
        }
        if ([captureMetadataOutput.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeCode128Code]) {
            [array addObject:AVMetadataObjectTypeCode128Code];
        }
        captureMetadataOutput.metadataObjectTypes = array;
    }
    
    //6.实例化预览图层
    _videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSessionWithNoConnection:_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
    CGFloat width = _viewPreview.bounds.size.width ;
    CGFloat height = _viewPreview.bounds.size.height;
    self.boxView = [[UIView alloc] initWithFrame:CGRectMake(width * 0.2f, height * 0.2f, width - width * 0.4f, height - height * 0.4f)];
    _boxView.layer.borderColor = [[UIColor greenColor] CGColor];
    _boxView.layer.borderWidth = 1.0f ;
    [_viewPreview addSubview:_boxView];
    //10.2扫描线
    self.scanLayer = [[CALayer alloc] init];
    _scanLayer.frame = CGRectMake(0, 0, _boxView.bounds.size.width, 1);
    _scanLayer.backgroundColor = [[UIColor brownColor] CGColor];
    [_boxView.layer insertSublayer:_scanLayer atIndex:0];
    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 ;
}


-(void)stopReading{
    [_captureSession stopRunning];
    _captureSession = nil;
    [_scanLayer removeFromSuperlayer];
    [_videoPreviewLayer removeFromSuperlayer];
}

#pragma mark --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;
        }];
    }
}

#pragma mark --初始化控件
-(void)initUI
{
    self.viewPreview = [[UIView alloc] init];
    self.viewPreview.frame = CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height -200);
//    self.viewPreview.backgroundColor = [UIColor clearColor];
//    self.viewPreview.alpha = 0.1f ;
    [self.view addSubview:_viewPreview];
    
    self.startBtn = [UIButton buttonWithType:UIButtonTypeSystem];
    _startBtn.frame = CGRectMake(100, self.view.bounds.size.height - 100, 175, 30);
    [_startBtn setTitle:@"开始" forState:UIControlStateNormal];
    [_startBtn addTarget:self action:@selector(startStopReading:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_startBtn];
}

#pragma mark --实现开始和停止方法
-(void)startStopReading:(UIButton *)btn
{
    if (!_isReading) {
        
        if ([self startReading]) {
            [_startBtn setTitle:@"停止" forState:UIControlStateNormal];
        }
    }
    else
    {
            [self stopReading];
            [_startBtn setTitle:@"开始" forState:UIControlStateNormal];
    }
    
    _isReading = !_isReading ;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


#pragma mark --实现AVCaptureMetadataOutputObjectsDelegate协议方法
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    if (metadataObjects.count > 0) {
        AVMetadataMachineReadableCodeObject *metadataObject = [metadataObjects firstObject];
         NSLog(@"................%@",metadataObject.stringValue);
        [self performSelectorOnMainThread:@selector(stopReading) withObject:nil waitUntilDone:NO];

    }
}


- (BOOL)shouldAutorotate
{
    return NO;
}
@end