繼昨天的實作練習，有相機，會執行以下的程式碼：

1. 令 vc 為 UIImagePickerController
   let vc = UIImagePickerController()
2. 新增相機權限
   vc.sourceType = .camera // 相簿
3. 設定委任
   vc.delegate = self
4. 允許用戶編輯選定的圖像或影像
   vc.allowsEditing = true
5. 設定跳頁
   present(vc, animated: true)

到這邊會報錯是正常的，因為沒給它 UIImagePickerControllerDelegate
因此在專案裡用 extension 去寫委任

extension MainVC: UIImagePickerControllerDelegate, UINavigationControllerDelegate{
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        // 顯示 photo
        guard let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {return}
        imageView.image = image
        picker.dismiss(animated: true, completion: nil)
    }
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        picker.dismiss(animated: true, completion: nil)
    }
}

附上完整程式碼

import UIKit

class MainVC: UIViewController {

    @IBOutlet weak var imageView: UIImageView!
    @IBOutlet weak var takePhoto: UIButton!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.navigationController?.setNavigationBarHidden(true, animated: false) // 隱藏指示條
    }
    
    @IBAction func didTapButton(btn: UIButton) {
        let vc = UIImagePickerController()
        if !UIImagePickerController.isSourceTypeAvailable(.camera) {
            let alertController = UIAlertController(title: "ERROR", message: "Device has no camera.", preferredStyle: .alert)
            let okAction = UIAlertAction(title: "Alright", style: .default, handler: { (alert: UIAlertAction!) in
            })
            alertController.addAction(okAction)
            self.present(alertController, animated: true, completion: nil)
            print("ERROR：沒有相機功能！")
        }
        else { vc.sourceType = .camera }
        vc.delegate = self
        present(vc, animated: true)
    }
}

extension MainVC: UIImagePickerControllerDelegate, UINavigationControllerDelegate{
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        picker.dismiss(animated: true, completion: nil)
        // 顯示 photo
        guard let image = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {return}
        imageView.image = image
    }
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        picker.dismiss(animated: true, completion: nil)
    }
}

為了測試和使用相機，您必須使用真正的連接設備，若燒在模擬器，會報錯：Source type 1 not available

這樣就完成從相簿選取照片的實作了！明天會分享從相簿選取照片（ 有裁剪照片功能 ），敬請期待！