本文讲述如何用系统自带的东东实现二维码扫描的功能:点击当前页面的某个按钮，创建扫描VIEW。细心的小伙伴可以发现 title被改变了，返回按钮被隐藏了。这个代码自己写就行了，与本文关系不大。。。绿色的线会上下跑，不要担心:D
实现效果如下：
1.在工程中添加框架AVFoundation.framework
2.声明代理：AVCaptureMetadataOutputObjectsDelegate 。 define 几个东东用来画框、画线：
#define SCANVIEW_EdgeTop 40.0#define SCANVIEW_EdgeLeft 50.0#define TINTCOLOR_ALPHA 0.2 //浅色透明度#define DARKCOLOR_ALPHA 0.5 //深色透明度#define VIEW_WIDTH [UIScreen mainScreen].bounds.size.width#define VIEW_HEIGHT [UIScreen mainScreen].bounds.size.height
3.声明以下属性：
AVCaptureSession * session;//输入输出的中间桥梁 UIView *AVCapView;//此 view 用来放置扫描框、取消按钮、说明 label UIView *_QrCodeline;//上下移动绿色的线条 NSTimer *_timer;
4.在某个方法中（我是点击扫描按钮）创建扫描界面，开始扫描：
//创建一个 view 来放置扫描区域、说明 label、取消按钮 UIView *tempView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 320, [UIScreen mainScreen].bounds.size.height )]; AVCapView = tempView; AVCapView.backgroundColor = [UIColor colorWithRed:54.f/255 green:53.f/255 blue:58.f/255 alpha:1]; UIButton *cancelBtn = [[UIButton alloc]initWithFrame:CGRectMake(15, [UIScreen mainScreen].bounds.size.height - 100, 50, 25)]; UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(15, 268, 290, 60)]; label.numberOfLines = 0; label.text = @"小提示：将条形码或二维码对准上方区域中心即可"; label.textColor = [UIColor grayColor]; [cancelBtn setTitle:@"取消" forState: UIControlStateNormal]; [cancelBtn setTitleColor:[UIColor grayColor] forState:UIControlStateNormal]; [cancelBtn addTarget:self action:@selector(touchAVCancelBtn) forControlEvents:UIControlEventTouchUpInside]; [AVCapView addSubview:label]; [AVCapView addSubview:cancelBtn]; [self.view addSubview:AVCapView]; //画上边框 UIView *topView = [[UIView alloc] initWithFrame:CGRectMake(SCANVIEW_EdgeLeft, SCANVIEW_EdgeTop, VIEW_WIDTH- 2 * SCANVIEW_EdgeLeft, 1)]; topView.backgroundColor = [UIColor whiteColor]; [AVCapView addSubview:topView]; //画左边框 UIView *leftView = [[UIView alloc] initWithFrame:CGRectMake(SCANVIEW_EdgeLeft, SCANVIEW_EdgeTop , 1,VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft )]; leftView.backgroundColor = [UIColor whiteColor]; [AVCapView addSubview:leftView]; //画右边框 UIView *rightView = [[UIView alloc] initWithFrame:CGRectMake(SCANVIEW_EdgeLeft + VIEW_WIDTH- 2 * SCANVIEW_EdgeLeft, SCANVIEW_EdgeTop , 1,VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft + 1)]; rightView.backgroundColor = [UIColor whiteColor]; [AVCapView addSubview:rightView]; //画下边框 UIView *downView = [[UIView alloc] initWithFrame:CGRectMake(SCANVIEW_EdgeLeft, SCANVIEW_EdgeTop + VIEW_WIDTH- 2 * SCANVIEW_EdgeLeft,VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft ,1 )]; downView.backgroundColor = [UIColor whiteColor]; [AVCapView addSubview:downView]; //画中间的基准线 _QrCodeline = [[UIView alloc] initWithFrame:CGRectMake(SCANVIEW_EdgeLeft + 1, SCANVIEW_EdgeTop, VIEW_WIDTH- 2 * SCANVIEW_EdgeLeft - 1, 2)]; _QrCodeline.backgroundColor = [UIColor greenColor]; [AVCapView addSubview:_QrCodeline]; // 先让基准线运动一次，避免定时器的时差 [UIView animateWithDuration:1.2 animations:^{ _QrCodeline.frame = CGRectMake(SCANVIEW_EdgeLeft + 1, VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft + SCANVIEW_EdgeTop , VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft - 1, 2); }]; [self performSelector:@selector(createTimer) withObject:nil afterDelay:0.4]; AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; //创建输入流 AVCaptureDeviceInput * input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil]; //创建输出流 AVCaptureMetadataOutput * output = [[AVCaptureMetadataOutput alloc]init]; //设置代理 在主线程里刷新 [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()]; //初始化链接对象 session = [[AVCaptureSession alloc]init]; //高质量采集率 [session setSessionPreset:AVCaptureSessionPresetHigh]; [session addInput:input]; [session addOutput:output]; //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.metadataObjectTypes=@[AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode128Code]; AVCaptureVideoPreviewLayer * layer = [AVCaptureVideoPreviewLayer layerWithSession:session]; layer.videoGravity=AVLayerVideoGravityResizeAspectFill; layer.frame = CGRectMake(SCANVIEW_EdgeLeft, SCANVIEW_EdgeTop, VIEW_WIDTH- 2 * SCANVIEW_EdgeLeft, 220); [AVCapView.layer insertSublayer:layer atIndex:0]; //开始捕获 [session startRunning]; 5.实现定时器、还有基准线的滚动方法
- (void)createTimer{ _timer=[NSTimer scheduledTimerWithTimeInterval:1.1 target:self selector:@selector(moveUpAndDownLine) userInfo:nil repeats:YES];}- (void)stopTimer{ if ([_timer isValid] == YES) { [_timer invalidate]; _timer = nil; } }// 滚来滚去 :D :D :D- (void)moveUpAndDownLine{ CGFloat YY = _QrCodeline.frame.origin.y; if (YY != VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft + SCANVIEW_EdgeTop ) { [UIView animateWithDuration:1.2 animations:^{ _QrCodeline.frame = CGRectMake(SCANVIEW_EdgeLeft + 1, VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft + SCANVIEW_EdgeTop , VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft - 1,2); }]; }else { [UIView animateWithDuration:1.2 animations:^{ _QrCodeline.frame = CGRectMake(SCANVIEW_EdgeLeft + 1, SCANVIEW_EdgeTop, VIEW_WIDTH - 2 * SCANVIEW_EdgeLeft - 1,2); }]; }} 6.扫描成功后，想干嘛干嘛，就在这个代理方法里面实现就行了
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{ if (metadataObjects.count>0) { //[session stopRunning]; AVMetadataMachineReadableCodeObject * metadataObject = [metadataObjects objectAtIndex : 0 ]; //输出扫描字符串 NSLog(@"%@",metadataObject.stringValue); [session stopRunning]; [self stopTimer]; [AVCapView removeFromSuperview]; ..... }}
7.如果用户不想扫描了，点击取消按钮：
- (void)touchAVCancelBtn{ [session stopRunning];//摄像也要停止 [self stopTimer];//定时器要停止 [AVCapView removeFromSuperview];//刚刚创建的 view 要移除 ... }