Set view controllers of UITabBarController in Swift

Question

I am trying to programatically set view controllers of my custom TabBarController:

import UIKit

class TabBarViewController: UITabBarController, UITabBarControllerDelegate {

var cameraViewController: UIViewController?
var profileViewController: UIViewController?

override func viewDidLoad() {
    super.viewDidLoad()

    self.delegate = self


    //self.viewControllers = [cameraViewController, profileViewController] as! [AnyObject]?
    let controllers: [UIViewController?] = [cameraViewController, profileViewController]
    self.setViewControllers(controllers as! [AnyObject], animated: true)

}

But with line

self.viewControllers = [cameraViewController, profileViewController] as! [AnyObject]?

I get an error that I cannot convert [UIViewController] to [AnyObject?]

and with line

self.setViewControllers(controllers as! [AnyObject], animated: true)

I get an error saying:

Cannot invoke 'setViewControllers' with an argument list of type '([AnyObject], animated: Bool)'

My problem is with AnyObject and typecasting I guess.

Answer 1

The problem is that the view controllers you are trying to use are declared optional:

var cameraViewController: UIViewController?
var profileViewController: UIViewController?

So you have three options:

• Don't make them optional. This requires that you initialize them with something when you initalize your TabBarViewController . Maybe the safest option.

• If you know that cameraViewController and profileViewController are never nil in viewDidLoad :

   self.viewControllers = [cameraViewController!, profileViewController!] 

• Check if cameraViewController and profileViewController are not nil in viewDidLoad . This smells like bad design to me though.

   if let c = cameraViewController, let p = profileViewController { self.viewControllers = [c, p] } 

So it boils down to how you initialize cameraViewController and profileViewController . Are they set before the tab bar view controllers is shown? If so, I recommend adding a custom init to your class.