ios oc 从手机选择文件

在iOS Objective-C中，如果你需要让用户从他们的设备上选择文件，例如照片或文档，你可以使用`UIImagePickerController`类。以下是一个简单的步骤描述：

1. 首先，在需要选择文件的地方导入`UIKit`框架，并创建一个UIImagePickerController对象：

#import <UIKit/UIKit.h>
UIImagePickerController *imagePickerController;

2. 实现一个方法来请求用户选择文件权限并显示选择界面：

- (void)selectFile {
    imagePickerController = [[UIImagePickerController alloc] init];
    imagePickerController.delegate = self; // 设置代理
    
    // 如果你想让用户选择图片，设置MediaType为UIImagePickerControllerSourceTypePhotoLibrary
    imagePickerController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        [self presentViewController:imagePickerController animated:YES completion:nil];
    }
}

3. 当用户完成选择后，需要实现`UIImagePickerControllerDelegate`协议的几个方法，如`imagePickerController:didFinishPickingMediaWithInfo:`来处理返回的数据：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<UIImagePickerControllerInfoKey,id> *)info {
    UIImage *selectedImage = info[UIImagePickerControllerOriginalImage]; // 对于照片
    // 或者其他文件路径，取决于你的需求
    
    // 将数据保存或进一步处理...
    [picker dismissViewControllerAnimated:YES completion:nil];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [picker dismissViewControllerAnimated:YES completion:nil];
}