Switch container view dynamically

Question

I\'m using a storyboard container view. So I have a view controller containing a container view. I have a second, smaller view in the storyboard, which is embedded in that c

Answer 1

If you deal with more than 2 child view controllers it's a good idea to store them in array. Also, you'll need to apply constraints every time you add a new subview to the container view. Here's a modified version of the accepted answer (using Swift 2 syntax):

import UIKit

class FooBarViewController: UIViewController
{
    // MARK: - IBOutlets

    @IBOutlet weak var containerView: UIView!

    // MARK: - Properties

    var vcs = [UIViewController]()
    var currentVC: UIViewController!

    // MARK: - ViewController Lifecycle

    override func viewDidLoad()
    {
        super.viewDidLoad()

        vcs.append(childViewControllers.last!)
        vcs.append(storyboard!.instantiateViewControllerWithIdentifier("FooViewControler"))       
        vcs.append(storyboard!.instantiateViewControllerWithIdentifier("BarViewController"))
        currentVC = vcs[0]

        for vc in vcs {
            vc.view.frame = containerView.bounds
        }
    }

    // MARK: - Methods

    func switchToViewController(targetVC: UIViewController)
    {
        addChildViewController(targetVC)
        currentVC.willMoveToParentViewController(nil)

        transitionFromViewController(
            currentVC,
            toViewController: targetVC,
            duration: 0.0, // 0.3
            options: .TransitionNone, // .TransitionCrossDissolve,
            animations: nil,
            completion: { finished in
                self.currentVC.removeFromParentViewController()
                targetVC.didMoveToParentViewController(self)
                self.currentVC = targetVC
                self.applyConstraints()
        })
    }

    func applyConstraints()
    {
        let viewsDict = ["newSubview": currentVC.view]

        currentVC.view.translatesAutoresizingMaskIntoConstraints = false

        containerView.addConstraints(
            NSLayoutConstraint.constraintsWithVisualFormat("H:|[newSubview]|",
                options: NSLayoutFormatOptions(rawValue: 0),
                metrics: nil,
                views: viewsDict))

        containerView.addConstraints(
            NSLayoutConstraint.constraintsWithVisualFormat("V:|[newSubview]|",
                options: NSLayoutFormatOptions(rawValue: 0),
                metrics: nil, views:
                viewsDict))
    }

    // MARK: - IBActions

    @IBAction func switchControllers(sender: UISegmentedControl)
    {
        let i = sender.selectedSegmentIndex

        if currentVC != vcs[i] {
            self.addChildViewController(vcs[i])
            switchToViewController(vcs[i])
        }
    }
}