self.tabBarController!.viewControllers返回nil

Question

我有一个TabBarController,它连接了四个不同的UIViews.TabBarController是从Controller.swift文件管理的,看起来像这样

import UIKit
import Firebase

class Controller: UITabBarController {

var firebaseUser = String()

override func viewDidLoad() {
    super.viewDidLoad()

    //let allVC = self.tabBarController?.viewControllers
    //let SearchVC = allVC![1] as! SearchVC
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

但是,被注释掉的行会导致错误"...在解包可选时发现nil .."(已经获得allVC导致错误)

我该如何解决这个错误？

Answer 1

请let allVC = self.viewControllers改用,因为您的类是UITabBarViewController子类