iOS摄像头初探

从摄像头获取照片和视频

• UIImagePickerController

• 可通过UIImagePickerController获取视频

  • 录制长达30min的视频
  • 将视频文件路径以NSString形式传递给应用程序

• 可设置使用前置或后置摄像头，是否使用LED灯，是否允许用户裁剪或调整照片或视频

• 工作方式：

  • 创建实例
  • 根据需要配置选取器
  • 选取器包含一个符合UIImagePickerControllerDelegate协议的委托对象
  • 当前的视图控制器通常会调用presentViewController:animated:completion:，所以视图控制器呈现为模态
  • 用户完成照片或视频后，委托对象接收imagePickerController:didFinishPickingMediaWithInfo:消息
    • 后者接收一个字典，包含用户获取的媒体信息
      • 原始或编辑过的照片
      • 视频文件位置
      • 或其他有用信息
    • 需调用dismissViewControllerAnimated:completion:释放图片选取器
  • 用户选择取消图片选择器，委托对象接收imagePickerControllerDidCancel:
    • 需调用dismissViewControllerAnimated:completion:释放图片选取器，否则，取消按钮不会起任何作用

• 判断有哪些摄像头可用+ isSourceTypeAvailable:

  if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
  {
      //摄像头存在至少一个摄像头
  }else
  {
      //摄像头不可用
  }
  

• 判断前置或后置摄像头是否可用+ isCameraDeviceAvailable:

  if([UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllercameraDeviceFront])
  {
      //前置摄像头可用
  }
  if([UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear])
  {
      //后置摄像头可用
  }
  

• 拍照实例部分代码

  - (IBAction)takePhoto:(id)sender
  {
          UIImagePickerController *pickerController = [[UIImagePickerController alloc]init];
  
          if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
          {
              //设置视图控制器控制摄像头
           pickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
      
              if ([UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront]) {
                  pickerController.cameraDevice = UIImagePickerControllerCameraDeviceFront;
          }else{
                  pickerController.cameraDevice = UIImagePickerControllerCameraDeviceRear;
          }
      
          pickerController.delegate = self;
          
          //将当前的视图控制器拿掉
          [self presentViewController:pickerController animated:YES completion:nil];
      }
  }
  
  //视图控制器的UIImagePickerControllerDelegate方法
  - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
  {
          UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
       self.imageView.image = image;
  
          [picker dismissViewControllerAnimated:YES completion:nil];
  }
  
  - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
  {
          [picker dismissViewControllerAnimated:YES completion:nil];
  }