判斷相機及相簿存取功能

由於iOS對於安全性的要求，APP在使用如麥克風、定位、相機、相簿等功能時會要求開發者詢問使用者，而使用者如果點擊不允許的話，就有可能造成APP崩潰，而有些使用這並不知道該去哪裡修改設定，所以如果能判斷目前是隱私權是不允許就彈出提示框，讓使用者可以直接轉至APP要求權限設定頁面去做設定，也是不錯的體驗。

以要求相簿及相機權限為例：

宣告方法：

func authorize() -> Bool {
  let photoLibraryStatus = PHPhotoLibrary.authorizationStatus() //相簿請求
  let camStatus = AVCaptureDevice.authorizationStatus(forMediaType: AVMediaTypeVideo) //相機請求
  switch (camStatus, photoLibraryStatus){ //判斷狀態
  case (.authorized,.authorized): //兩個都允許
    return true
  case (.notDetermined,.notDetermined): //兩個都還未決定,就請求授權
   AVCaptureDevice.requestAccess(forMediaType: AVMediaTypeVideo,  completionHandler: { (status) in
    DispatchQueue.main.async(execute: {
      _ = self.authorize()
    })
})
   PHPhotoLibrary.requestAuthorization({ (status) in
     DispatchQueue.main.async(execute: {
      _ = self.authorize()   
    })
})
   case (.authorized,.notDetermined): //相機允許，相簿未決定，相簿請求授權
   PHPhotoLibrary.requestAuthorization({ (status) in
    DispatchQueue.main.async(execute: {
     _ = self.authorize()
    })
})
   case (.authorized,.denied): //相機允許，相簿拒絕，做出提醒
    let alertController = UIAlertController(title: "提醒❗️", message: "您目前拍攝的照片並不會儲存至相簿，要前往設定嗎?", preferredStyle: .alert)
    let canceAlertion = UIAlertAction(title: "取消", style: .cancel, handler: {(status) in
    UIImagePickerController.isSourceTypeAvailable(.camera)
    let photoImagePC = UIImagePickerController()
    photoImagePC.delegate = self
    photoImagePC.sourceType = .camera
    self.show(photoImagePC, sender: self)
   })
    let settingAction = UIAlertAction(title: "設定", style: .default, handler: { (action) in
    let url = URL(string: UIApplicationOpenSettingsURLString)
    if let url = url, UIApplication.shared.canOpenURL(url) {
     if #available(iOS 10.0, *) {
       UIApplication.shared.open(url, options: [:], completionHandler: { (success) in
        print("跳至設定")   
     })
    } else {
        UIApplication.shared.openURL(url)
      }
    }
})
   alertController.addAction(canceAlertion)
   alertController.addAction(settingAction)
   self.present(alertController, animated: true, completion: nil)
   default: //預設，如都不是以上狀態
DispatchQueue.main.async(execute: {
    let alertController = UIAlertController(title: "提醒❗️", message: "請點擊允許才可於APP內開啟相機及儲存至相簿", preferredStyle: .alert)
    let canceAlertion = UIAlertAction(title: "取消", style: .cancel, handler: nil)
    let settingAction = UIAlertAction(title: "設定", style: .default, handler: { (action) in
    let url = URL(string: UIApplicationOpenSettingsURLString)
    if let url = url, UIApplication.shared.canOpenURL(url) {
      if #available(iOS 10.0, *) {
    UIApplication.shared.open(url, options: [:], completionHandler: { (success) in
    print("跳至設定")
     })
  } else {
     UIApplication.shared.openURL(url)
     }
   }
})
   alertController.addAction(canceAlertion)
   alertController.addAction(settingAction)
   self.present(alertController, animated: true, completion: nil)
     })
   }
    return false
}
}

此功能是參考此連結https://www.hangge.com/blog/cache/detail_1517.html。