ios 读取本地图片到NSdata

在iOS中，读取本地图片并将其转换为NSData对象通常通过UIImagePickerController或UIImage类来完成。以下是基本步骤：

1. 首先，你需要导入相关的框架：

import UIKit

2. 使用UIImagePickerController让用户选择图片：

let imagePickerController = UIImagePickerController()
imagePickerController.sourceType = .photoLibrary
imagePickerController.delegate = self // 确保你的视图控制器实现了UIImagePickerControllerDelegate和UINavigationControllerDelegate协议

if let sourceViewController = UIApplication.shared.keyWindow?.rootViewController {
    sourceViewController.present(imagePickerController, animated: true, completion: nil)
}

3. 当用户选择图片后，在`UIImagePickerControllerDelegate`方法里获取UIImage对象，并将其转化为NSData：

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    guard let selectedImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else { return }
    
    do {
        let imageData = try selectedImage.jpegData(compressionQuality: 0.8) // 或者pngData等，根据需要选择压缩质量
        // imageData就是你想要的NSData对象了
    } catch {
        print("Failed to convert image to data: \(error)")
    }

    dismiss(animated: true, completion: nil)
}

4. 最后记得处理取消选择或关闭相机的情况。