iOS应用程序在swift撤销后冻结

My issue is this I have two viewControllers connected with a modal segue like normal A--->B, A has the controls like textFields, switches, buttons and a mapView where I get the userLocation. B hast only a button, and a mapView at the moment, but when I tap the exit button it does successfully dismisses viewController B and shows A only controls are frozen, can't tap anything anymore, I don't know why. Any help?My issue is this I have two viewControllers con