通常我們用到的二維碼掃描可能還是首先想到ZXing或者ZBar，但是用第三方的會有很多不變，第一是因入庫文件占用內(nèi)存較大，第二就是使用不方便，效率不夠高；所以在iOS7系統(tǒng)中蘋果引入了自己的二維碼掃描機制，那效率必然是無話可說的，廢話不多說，直接開始——

1.引入頭文件

#import <AVFoundation/AVFoundation.h>

2.聲明相關(guān)類屬性

//設(shè)備屬性
@property (strong,nonatomic)AVCaptureDevice *device;
@property (strong,nonatomic)AVCaptureDeviceInput *input;
@property (strong,nonatomic)AVCaptureMetadataOutput *output;
@property (strong,nonatomic)AVCaptureSession *session;
@property (strong,nonatomic)AVCaptureVideoPreviewLayer *preview;

3.設(shè)置代理方法

@interface TA_qrcode_home ()<AVCaptureMetadataOutputObjectsDelegate>

4.掃描主體實現(xiàn)

#pragma mark -----初始化相機設(shè)備等掃描控件------
- (void)setupCamera
{
    // Device
    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    if(_device == nil)
    {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"未檢測到相機設(shè)備" message:@"未檢測到相機設(shè)備" delegate:self cancelButtonTitle:nil otherButtonTitles:@"確定", nil];
        [alert show];
        return ;
    }
    // Input
    _input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
    // Output
    _output = [[AVCaptureMetadataOutput alloc]init];
    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    // Session
    _session = [[AVCaptureSession alloc]init];
    //限制掃描區(qū)域
    CGSize size = self.view.bounds.size;
    CGRect cropRect = self.sweepFrame;
    CGFloat p1 = size.height/size.width;
    CGFloat p2 = 1920./1080.;  //使用了1080p的圖像輸出
    if (p1 < p2) {
        CGFloat fixHeight = size.width * 1920. / 1080.;
        CGFloat fixPadding = (fixHeight - size.height)/2;
        _output.rectOfInterest = CGRectMake((cropRect.origin.y + fixPadding)/fixHeight,cropRect.origin.x/size.width,cropRect.size.height/fixHeight,cropRect.size.width/size.width);
    } else {
        CGFloat fixWidth = size.height * 1080. / 1920.;
        CGFloat fixPadding = (fixWidth - size.width)/2;
        _output.rectOfInterest = CGRectMake(cropRect.origin.y/size.height,(cropRect.origin.x + fixPadding)/fixWidth,cropRect.size.height/size.height,cropRect.size.width/fixWidth);
    }
    [_session setSessionPreset:AVCaptureSessionPresetHigh];
    if ([_session canAddInput:self.input])
    {
        [_session addInput:self.input];
    }
    
    if ([_session canAddOutput:self.output])
    {
        [_session addOutput:self.output];
    }
    NSLog(@"%@",[_output availableMetadataObjectTypes]);
    // 掃碼類型 AVMetadataObjectTypeQRCode，此為支持所有掃描類型
    [_output setMetadataObjectTypes:[NSArray arrayWithObjects:AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypeQRCode, nil]];
    // Preview
    _preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];
    _preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
    _preview.frame =CGRectMake(0,0,ScreenFrameWidth,ScreenFrameHeight-44);
    [self.view.layer insertSublayer:self.preview atIndex:0];
    // Start
    [_session startRunning];
}

5.如何做到掃描區(qū)域的限制
參看連接，非常詳盡講解：http://www.itdecent.cn/p/3fb24fc7b415

6.代理回調(diào)方法

#pragma mark -----AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    
    if ([metadataObjects count] >0)
    {
        AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex:0];
        
        self.resultStr = metadataObject.stringValue;
    }
    [self stopDevice];
    ...
}
-(void)stopDevice
{
    [_session stopRunning];
    _session = nil;
    [self.preview removeFromSuperlayer];
    [self.sweepViewHandler.timer invalidate];
}

7.視圖區(qū)域的繪制（好多人以為這個設(shè)置出來效果就是我們平時的視圖小效果就是調(diào)用設(shè)備即可，其實不然，是需要手動繪制的，這里不多贅述）

這篇文章寫得不錯，有需要可以參考 http://www.itdecent.cn/p/05949cc8f7af