How to get Root view controller in Swift

In this article, I will show you a quick and dirty way to get a root view controller in an iOS app.

Before iOS 13, you might use the following code to get a key window or a root view controller.

UIApplication.shared.keyWindow?.rootViewController
// Or
UIApplication.shared.windows.first?.rootViewController

But in iOS 13, iOS add is supporting multiple scenes and windows. This makes a concept of a single key window obsolete.

Apple deprecated UIApplication.shared.keyWindow and UIApplication.shared.windows in iOS 13, and iOS 15, respectively.

How to get Root view controller in iOS

So, to get a key window or root view controller in iOS 13 onward, we should use something like this.

extension UIApplication {
    var firstKeyWindow: UIWindow? {
        // 1
        let windowScenes = UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
        // 2
        let activeScene = windowScenes
            .filter { $0.activationState == .foregroundActive }
        // 3
        let firstActiveScene = activeScene.first
        // 4
        let keyWindow = firstActiveScene?.keyWindow
        
        return keyWindow
    }
}

1 We get all scenes with UIApplication.shared.connectedScenes and compact map them to UIWindowScene, which is the scene that we are interested.
2 Then, we filter only an active scene. Multiple windows support means we can get more than one active scene here.
3 We grab the first scene from array of all active scenes.
4 Then we get a key window from that scene.

Then we can get a root view controller like this.

let vc = UIApplication.shared.firstKeyWindow?.rootViewController

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Quick and Dirty

I mentioned that this is a quick and dirty implementation because there is a chance that there are two active scenes and we don't really care which one is calling this method.

extension UIApplication {
    var firstKeyWindow: UIWindow? {
        let windowScenes = UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
        // 1
        let activeScene = windowScenes
            .filter { $0.activationState == .foregroundActive }
        // 2
        let firstActiveScene = activeScene.first
        let keyWindow = firstActiveScene?.keyWindow
        
        return keyWindow
    }
}

1 There is a chance that there is more than one active scene.
2 We just randomly picked the first one in this implementation.

As a result, the root view you get might not be the same one that was calling it.