single function to dismiss all open view controllers

You can call :

self.view.window!.rootViewController?.dismiss(animated: false, completion: nil)

Should dismiss all view controllers above the root view controller.

ios swift uiviewcontroller dismiss

Updated answer for Swift 4 and swift 5

UIApplication.shared.keyWindow?.rootViewController?.dismiss(animated: true, completion: nil)

and when you use navigationController

self.navigationController?.popToRootViewController(animated: true)

ios swift uiviewcontroller dismiss

Works for Swift 4 and Swift 5

To dismiss any unwanted residue Modal ViewControllers, I used this and worked well without retaining any navigation stack references.

UIApplication.shared.keyWindow?.rootViewController?.dismiss(animated: false, completion: nil)

self.view.window! did crash for my case possibly because its a Modal screen and had lost the reference to the window.

CodeHunter