iOS实现二维码的扫描功能

直接上代码，就不多废话了

//
// ViewController.m
// QRCode
//
// Created by chenchen on 15/7/30.
// Copyright (c) 2015年 BSY. All rights reserved.
//
#import 
#import "ViewController.h"
@interface ViewController ()
 
@end
 
@implementation ViewController
 
- (void)viewDidLoad {
  [super viewDidLoad];
  
   
   
  AVCaptureSession *session = [[AVCaptureSession alloc] init];
  AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
  NSError *error = nil;
   
  AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device
 error:&error];
  if (input) {
    [session addInput:input];
  } else {
    NSLog(@"Error: %@", error);
  }
  AVCapturemetadataOutput *output = [[AVCapturemetadataOutput alloc] init];
  //设置扫码支持的编码格式(如下设置条形码和二维码兼容)
  [output setmetadataObjectTypes:@[AVmetadataObjectTypeQRCode,AVmetadataObjectTypeEAN13Code, AVmetadataObjectTypeEAN8Code, AVmetadataObjectTypeCode128Code]];
  [output setmetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
  [session addOutput:output];
  [session startRunning];
}
 
#pragma mark - AVCapturemetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputmetadataObjects:(NSArray *)metadataObjects
    fromConnection:(AVCaptureConnection *)connection
{
  NSString *QRCode = nil;
  for (AVmetadataObject *metadata in metadataObjects) {
    if ([metadata.type isEqualToString:AVmetadataObjectTypeQRCode]) {
      // This will never happen; nobody has ever scanned a QR code... ever
      QRCode = [(AVmetadataMachineReadableCodeObject *)metadata stringValue];
      break;
    }
  }
   
  NSLog(@"QR Code: %@", QRCode);
}
- (void)didReceiveMemoryWarning {
  [super didReceiveMemoryWarning];
  // Dispose of any resources that can be recreated.
}
 
@end