My IOS tab bar app has both bright and dark display modes. To make this work well, I want to set the tab bar appearance accordingly to display mode. I have the following code in place to do this.
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
displayMode=UserDefaults.standard.integer(forKey: "displayMode")
if displayMode==0 // bright display. want bright tab bar
{ UITabBar.appearance().backgroundColor=UIColor.white
UITabBar.appearance().barTintColor=UIColor.white
UITabBar.appearance().unselectedItemTintColor = UIColor.darkGray
UITabBar.appearance().tintColor = UIColor.blue
UITabBar.appearance().isTranslucent = false
}
if displayMode==1 // dark display. want dark tab bar
{ UITabBar.appearance().backgroundColor=UIColor.black
UITabBar.appearance().barTintColor=UIColor.black
UITabBar.appearance().unselectedItemTintColor = UIColor.lightGray
UITabBar.appearance().tintColor = UIColor.white
UITabBar.appearance().isTranslucent = false
}
return true
}
This works but poorly. It can only change the tab bar colors when the app restarts. I would like to make it more immediate. The choice of places to put the controls appears limited to the App Delegate. I would like to control the tab bar colors from my main program area instead.
Appearance
proxy is not limited to AppDelegate
. You can apply it anywhere anytime but note the following:
iOS applies appearance changes when a view enters a window, it doesn’t change the appearance of a view that’s already in a window. To change the appearance of a view that’s currently in a window, remove the view from the view hierarchy and then put it back.
Ref: https://developer.apple.com/documentation/uikit/uiappearance
Present and dismiss a dummy UIViewController
. Thereby refreshing the visible viewController
of the window.
Example:
func randomTabBarAppearance() {
UITabBar.appearance().backgroundColor = UIColor.init(red: CGFloat.random(in: 0...1),
green: CGFloat.random(in: 0...1),
blue: CGFloat.random(in: 0...1),
alpha: 1)
present(UIViewController(), animated: false, completion: nil)
dismiss(animated: false, completion: nil)
}