iOS 选取用户相册中的图片 UIImagePickerController Swift

iOS 选取用户相册中的图片 UIImagePickerController

[ GitHub] iOS Demo ： https://github.com/KyleBing/iosDemo
该文中的例子能够从上面这个 github 项目中找到，包含许多其它经常使用 UI 组件的使用

选取用户相册中图片，或者拍照的方式经过 UIImagePickerController 来实现

内容

从相册中选取一张图片，并按比例显示在当前 ViewController 的中间位置

步骤

VC = ViewController 方便说明，因此简写

1. 在当前 VC 中 实现 UIImagePickerControllerDelegate、UINavigationController 这两个协议
2. 新建一个 picker: UIImagePickerController 和 imageView: UIImageView
3. 设置这个 picker 的 delegate 是 当前 VC
4. 设置 imageView 的内容展现属性：比例缩放
5. 设置选取照片的触发方法，好比在 NavigationBar 中添加一个按钮

6. 实现 UIImagePickerControllerDelegate 的两个方法

   1. 用户选中一张图片时：获取 info 中的信息并进行相关操做，最后使选择窗口消失
   2. 用户取消选择时，使选择窗口消失

效果

代码及注释

//
//  ImagePickerVC.swift
//  iosDemo
//
//  Created by Kyle on 2020/3/16.
//  Copyright © 2020 KyleBing. All rights reserved.
//

import UIKit

/// 0. 这个 ViewController  须要实现 UIImagePickerControllerDelegate 和 UINavigationControllerDelegate 两个协议
class ImagePickerVC: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    /// 1. 新建 UIImagePickerController 对象
    var imagePicker: UIImagePickerController = UIImagePickerController()
    lazy var imageView = UIImageView(frame: view.frame)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Pick", style: .plain, target: self, action: #selector(pickAnImage))
        /// 2. 设置 picker 的 delegate 和 相关设置
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary
        /// 3. 设置 imageView 的属性
        imageView.contentMode = .scaleAspectFit
        view.addSubview(imageView)
    }
    
    
    @objc func pickAnImage(){
        /// 4. 点击选图片时，展现这个 picker controller
        present(imagePicker, animated: true) {
            print("UIImagePickerController: presented")
        }
    }
    
    // MARK: - Image picker delegate
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        /// 5. 用户选中一张图片时触发这个方法，返回关于选中图片的 info
        /// 6. 获取这张图片中的 originImage 属性，就是图片自己
        guard let selectedImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {
            fatalError("error: did not picked a photo")
        }
        /// 7. 根据须要作其它相关操做，这里选中图片之后关闭 picker controller 便可
        picker.dismiss(animated: true) { [unowned self] in
            // add a image view on self.view
            self.imageView.image = selectedImage
        }
    }
    
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        /// 8. 用户点击取消时
        picker.dismiss(animated: true) {
            print("UIImagePickerController: dismissed")
        }
    }
}

info 内容

__C.UIImagePickerControllerInfoKey(_rawValue: UIImagePickerControllerReferenceURL): assets-library://asset/asset.JPG?id=557741A9-A05A-468E-AFAB-9B759CB66660&ext=JPG
__C.UIImagePickerControllerInfoKey(_rawValue: UIImagePickerControllerOriginalImage): <UIImage:0x283e360a0 anonymous {2048, 1536}>
__C.UIImagePickerControllerInfoKey(_rawValue: UIImagePickerControllerMediaType): public.image
__C.UIImagePickerControllerInfoKey(_rawValue: UIImagePickerControllerImageURL): file:///private/var/mobile/Containers/Data/Application/A5875FF6-3D3C-4147-BF5B-AD850397694D/tmp/CC744A41-B42F-490E-9B5F-5AF06CDD24C4.jpeg]