注意：本篇文章采用了IOS7的新特性來掃二維碼，所以系統支持要IOS7以上，如果要兼容IOS7之前的版本，自行找庫來支持。

為了方便，我把掃二維碼簡單封裝到了一個UIView中，用代理的方式返回值

在使用之前，應當為工程添加AVFoundation.framework

最后實現的效果如圖

完整的實現代碼

頭文件

//
//  HwcScanQRView.h
//  HwcAnimationExample
//
//  Created by huangwenchen on 15/1/7.
//  Copyright (c) 2015年 huangwenchen. All rights reserved.
//

import <UIKit/UIKit.h>
@protocol HwcScanQRDelegate <NSObject>
/*!

@discussion Delegate method when scan QR successed
@param QRContent Scan result
@return Void
*/

-(void)DidGetScanWithResult:(NSString )QRContent;
/!

@discussion Delegate method when scan QR failed
@param error Error message
@return Void
/
-(void)DidFailToScanWithError:(NSError )error;
@end

@interface HwcScanQRView : UIView
@property id<HwcScanQRDelegate> delegate;
@property(nonatomic,readonly) bool isScaning;
-(BOOL)startScaning;
-(void)stop;
@end
</pre> .m文件
 
 

 
 

//
//  HwcScanQRView.m
//  HwcAnimationExample
//
//  Created by huangwenchen on 15/1/7.
//  Copyright (c) 2015年 huangwenchen. All rights reserved.
//

import "HwcScanQRView.h"
import  <AVFoundation/AVFoundation.h>
@interface HwcScanQRView()<AVCaptureMetadataOutputObjectsDelegate>
@property(nonatomic,readwrite) bool isScaning;
@property(strong,nonatomic)AVCaptureSession  captureSession;
@property(strong,nonatomic)AVCaptureVideoPreviewLayer  vedioPreviewLayer;
@end
@implementation HwcScanQRView
pragma mark - Propertys
-(AVCaptureSession *)captureSession{
    if (!_captureSession) {
        _captureSession = [[AVCaptureSession alloc] init];
    }
    return  _captureSession;
}
-(AVCaptureVideoPreviewLayer *)vedioPreviewLayer{
    if (!_vedioPreviewLayer) {
        _vedioPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
    }
    return _vedioPreviewLayer;
}
pragma mark - QRScan function
-(BOOL)startScaning{
    NSError  error;
    AVCaptureDevice  captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput  deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];
    if (!deviceInput) {
        if ([self.delegate respondsToSelector:@selector(DidFailToScanWithError:)]) {
            [self.delegate DidFailToScanWithError:error];
        }
        return NO;
    }
    [self.captureSession addInput:deviceInput];
    AVCaptureMetadataOutput  captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
    [self.captureSession addOutput:captureMetadataOutput];
    dispatch_queue_t scanQRqueue;
    scanQRqueue = dispatch_queue_create("scanQRqueue",DISPATCH_QUEUE_SERIAL);
    [captureMetadataOutput setMetadataObjectsDelegate:self queue:scanQRqueue];
    [captureMetadataOutput setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
    [self.vedioPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [self.vedioPreviewLayer setFrame:self.layer.bounds];
    [self.layer addSublayer:self.vedioPreviewLayer];
    [self.captureSession startRunning];
    return YES;
}
-(void)stop{
    [self.captureSession stopRunning];
    self.isScaning = NO;
    self.captureSession = nil;
    [_vedioPreviewLayer removeFromSuperlayer];
}
pragma mark - AVFoundation delegate method
-(void)captureOutput:(AVCaptureOutput )captureOutput didOutputMetadataObjects:(NSArray )metadataObjects fromConnection:(AVCaptureConnection )connection
{
    if (metadataObjects != nil && metadataObjects.count > 0) {
        AVMetadataMachineReadableCodeObject  metadataObject = [metadataObjects firstObject];
        if ([[metadataObject type] isEqualToString:AVMetadataObjectTypeQRCode]) {
            NSString * scanResult = [metadataObject stringValue];
            dispatch_async(dispatch_get_main_queue(), ^{
                if ([self.delegate respondsToSelector:@selector(DidGetScanWithResult:)]) {
                    [self.delegate DidGetScanWithResult:scanResult];
                }
            });
        }
    }
}
@end
</pre> 

 在使用的類中
 
 

 
 

//
//  ViewController.m
//  HwcAnimationExample
//
//  Created by huangwenchen on 15/1/6.
//  Copyright (c) 2015年 huangwenchen. All rights reserved.
//

import "ViewController.h"
import "HwcScanQRView.h"
@interface ViewController ()<HwcScanQRDelegate>//這里實現代理
@property (strong,nonatomic)UILabel * scanresultLabel;
@end
@implementation ViewController

(void)viewDidLoad {
  [super viewDidLoad];
  HwcScanQRView  scanView = [[HwcScanQRView alloc] initWithFrame:CGRectMake(100,100,200, 200)];
  scanView.delegate = self;//這一步必須的
  [self.view addSubview:scanView];
  self.scanresultLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 320, 200, 30)];
  [self.view addSubview:self.scanresultLabel];
  [scanView startScaning];//不要忘記開始掃描
}
//兩個代理方法
-(void)DidGetScanWithResult:(NSString )QRContent{
  self.scanresultLabel.text = QRContent;
}
-(void)DidFailToScanWithError:(NSError *)error{
  NSLog(@"%@",error.localizedDescription);
}

@end</pre> 

 來自：
blog.csdn.net/hello_hwc