使用Cocoa Touch如何访问并修改用户的照片库

要访问和修改用户的照片库，可以使用UIImagePickerController类和UIImagePickerDelegate协议。以下是一个简单的示例代码，演示如何访问用户的照片库并显示选定的图片：

// 在视图控制器中创建一个UIImagePickerController属性 @property (nonatomic, strong) UIImagePickerController *imagePickerController; // 实例化UIImagePickerController并设置代理 self.imagePickerController = [[UIImagePickerController alloc] init]; self.imagePickerController.delegate = self; // 设置UIImagePickerController的sourceType为UIImagePickerControllerSourceTypePhotoLibrary，以访问用户的照片库 self.imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary; // 显示UIImagePickerController [self presentViewController:self.imagePickerController animated:YES completion:nil]; // 实现UIImagePickerDelegate协议方法，处理用户选择的图片 - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info { UIImage *selectedImage = info[UIImagePickerControllerOriginalImage]; // 在这里可以对选定的图片进行处理或保存到本地 // 关闭UIImagePickerController [picker dismissViewControllerAnimated:YES completion:nil]; } // 实现UIImagePickerDelegate协议方法，处理用户取消选择 - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker { // 关闭UIImagePickerController [picker dismissViewControllerAnimated:YES completion:nil]; } 

这段代码演示了如何访问用户的照片库并显示选定的图片。您可以在didFinishPickingMediaWithInfo方法中对选定的图片进行处理，例如显示在UIImageView中，保存到本地等操作。在imagePickerControllerDidCancel方法中处理用户取消选择的情况。