UIImagePickerController使用教程

UIImagePickerController是一个非常实用的控制器，它可以帮助我们从相机、相册或图库获取媒体。以下是如何使用UIImagePickerController的详细教程。
一、导入头文件
在你的ViewController中引入这两个协议：

#import <UIKit/UIKit.h>
#import <Photos/Photos.h>

并且在.h文件中添加一个UIImagePickerController对象：

@interface YourViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@property (nonatomic, strong) UIImagePickerController *imagePicker;
@end

二、基本使用

1. 从相册获取媒体
   从当前页面进入媒体选择页面：

   if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
   UIImagePickerController *imagePickerVC = [[UIImagePickerController alloc] init];
   imagePickerVC.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
   imagePickerVC.delegate = self;
   [self presentViewController:imagePickerVC animated:YES completion:nil];
   }

   在用户选择了一张照片后，我们需要实现UIImagePickerControllerDelegate协议中的imagePickerController方法来获取用户选择的照片：
   ```objective

• (void)imagePickerController:(UIImagePickerController )picker didFinishPickingMediaWithInfo:(NSDictionary )info {
  UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
  // 在这里使用选择的图片
  [self dismissViewControllerAnimated:YES completion:nil];
  }
  ```

1. 从相机获取媒体
   首先，我们需要检查相机是否可用：

   if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
   UIImagePickerController *imagePickerVC = [[UIImagePickerController alloc] init];
   imagePickerVC.sourceType = UIImagePickerControllerSourceTypeCamera;
   imagePickerVC.delegate = self;
   [self presentViewController:imagePickerVC animated:YES completion:nil];
   }

   同样，在用户拍完照片后，我们需要实现UIImagePickerControllerDelegate协议中的imagePickerController方法来获取用户拍摄的照片：
   ```objective

• (void)imagePickerController:(UIImagePickerController )picker didFinishPickingMediaWithInfo:(NSDictionary )info {
  UIImage *chosenImage = info[UIImagePickerControllerOriginalImage];
  // 在这里使用拍摄的图片
  [self dismissViewControllerAnimated:YES completion:nil];
  }
  ```

1. 定制相机界面
   如果你想定制相机界面，你可以通过设置cameraCaptureMode和cameraDevice属性来实现。例如，如果你想让相机以正方形模式拍照，你可以这样做：

   imagePickerVC.cameraCaptureMode = UIImagePickerControllerCameraCaptureModeSquare;

   如果你想指定相机设备（前置或后置），你可以这样做：

   imagePickerVC.cameraDevice = UIImagePickerControllerCameraDeviceRear;