拒绝日历访问时显示警报Swift 3

   eventStore.requestAccess(to: .event) { (granted, error) in

       if granted {

           // 用户授权访问日历

           // 在这里执行相关操作

       } else {

           // 用户拒绝访问日历

           DispatchQueue.main.async {

               showCalendarAccessDeniedAlert()

           }

       }

   }

   let alert = UIAlertController(title: "无法访问日历", message: "请在设置中允许应用程序访问您的日历。", preferredStyle: .alert)

   let settingsAction = UIAlertAction(title: "设置", style: .default) { (_) in

       if let settingsURL = URL(string: UIApplication.openSettingsURLString) {

           UIApplication.shared.open(settingsURL, options: [:], completionHandler: nil)

       }

   }

   let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)

   alert.addAction(settingsAction)

   alert.addAction(cancelAction)

   present(alert, animated: true, completion: nil)