call_directory_extension_1.swift

import CallKit
//
//......
//
if #available(iOS 10.0, *) {
    CXCallDirectoryManager.sharedInstance.getEnabledStatusForExtension(withIdentifier: "這裡輸入call directory extension的bundle identifier", completionHandler: { (status, error) in
        if status == .enabled {
          //啟用中
        } else if status == .disabled {
          //未啟用
        } else {
          //未知,不支援
        }
    })
}