iOS 選取用戶相冊中的圖片 UIImagePickerController Swift

iOS 選取用戶相冊中的圖片 UIImagePickerController

[ GitHub] iOS Demo ： https://github.com/KyleBing/iosDemo
該文中的例子能夠從上面這個 github 項目中找到，包含許多其它經常使用 UI 組件的使用

選取用戶相冊中圖片，或者拍照的方式經過 UIImagePickerController 來實現

內容

從相冊中選取一張圖片，並按比例顯示在當前 ViewController 的中間位置

步驟

VC = ViewController 方便說明，因此簡寫

1. 在當前 VC 中 實現 UIImagePickerControllerDelegate、UINavigationController 這兩個協議
2. 新建一個 picker: UIImagePickerController 和 imageView: UIImageView
3. 設置這個 picker 的 delegate 是 當前 VC
4. 設置 imageView 的內容展現屬性：比例縮放
5. 設置選取照片的觸發方法，好比在 NavigationBar 中添加一個按鈕

6. 實現 UIImagePickerControllerDelegate 的兩個方法

   1. 用戶選中一張圖片時：獲取 info 中的信息並進行相關操做，最後使選擇窗口消失
   2. 用戶取消選擇時，使選擇窗口消失

效果

代碼及註釋

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

import UIKit

/// 0. 這個 ViewController  須要實現 UIImagePickerControllerDelegate 和 UINavigationControllerDelegate 兩個協議
class ImagePickerVC: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    /// 1. 新建 UIImagePickerController 對象
    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. 設置 picker 的 delegate 和 相關設置
        imagePicker.delegate = self
        imagePicker.sourceType = .photoLibrary
        /// 3. 設置 imageView 的屬性
        imageView.contentMode = .scaleAspectFit
        view.addSubview(imageView)
    }
    
    
    @objc func pickAnImage(){
        /// 4. 點擊選圖片時，展現這個 picker controller
        present(imagePicker, animated: true) {
            print("UIImagePickerController: presented")
        }
    }
    
    // MARK: - Image picker delegate
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        /// 5. 用戶選中一張圖片時觸發這個方法，返回關於選中圖片的 info
        /// 6. 獲取這張圖片中的 originImage 屬性，就是圖片自己
        guard let selectedImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {
            fatalError("error: did not picked a photo")
        }
        /// 7. 根據須要作其它相關操做，這裏選中圖片之後關閉 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. 用戶點擊取消時
        picker.dismiss(animated: true) {
            print("UIImagePickerController: dismissed")
        }
    }
}

info 內容

__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]