如何更改UIViewController的背景颜色

Question

I have a MainViewController and it has a container view. with few margin from edges.
Now i navigate to another view ViewController1. Suppose there i get an error for some region in ViewController1. then i want to change my MainViewController's background in red. so the view should look like this(screen shot are attached) where red border is MainViewController Background

and here is my code

class ViewController1: UIViewController {
var MainVC =  MainViewController()
     override func viewDidLoad() {
        super.viewDidLoad()
        MainVC.view.backgroundColor = UIColor.redColor()
    }

but its not working

Answer 1

尝试这个 ：

self.view.backgroundColor = UIColor. greenColor()

Answer 2

You can get any uiviewcontroller object from Navigation controller:

navigationController?.viewControllers;