Wsrtjtyk

I'm trying to find the best approach about changing color theme of an app. After my investigations I inspired Durul Dalkanat's post on https://medium.com/@duruldalkanat/part-2-installing-theme-manager-18a32c314cf1 and wrote below codes in order to apply to my app.

My problem is that the color theme doesn't change when user switch the switch button.

If necessary to explain in a detailed manner

I created an enumeration that includes my colors.

enum ColorTheme: Int {

case day, night



var mainColor:UIColor {

    switch self {

    case .day:

        return UIColor().hexToUIColor("D9D8C8")

    case .night:

        return UIColor().hexToUIColor("141B1B")



    }

}}

And then I created a struct in order to apply my color theme to all components in my app and set to user defaults and get from there like below.

let selectedThemeKey = "SelectedTheme"



struct ThemeManager {



static func currentTheme() -> ColorTheme {



    if let storedTheme = (UserDefaults.standard.value(forKey: selectedThemeKey) as AnyObject).integerValue {

        return ColorTheme(rawValue: storedTheme)!

    } else {

        return .night

    }

}



static func applyTheme(theme:ColorTheme){



    UserDefaults.standard.set(theme.rawValue, forKey: selectedThemeKey)

    UserDefaults.standard.synchronize()



    UITabBar.appearance().backgroundColor = currentTheme().mainColor

}}

And then I added my code to
didFinishLaunchWithOptions method in AppDelegate

let defaultTheme = ThemeManager.currentTheme()



func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    // Override point for customization after application launch.



    let defaultTheme = ThemeManager.currentTheme()

    ThemeManager.applyTheme(theme: defaultTheme)

    return true



}

Finally I added a UISwitch to my SettingViewController to change my color theme and I want to manage my color theme with in its action as below.

let appDelegate = UIApplication.shared.delegate as! AppDelegate



@IBAction func colorModeSwitchSwiped(_ sender: UISwitch) {





    if colorModeSwitch.isOn {

        ThemeManager.applyTheme(theme: ColorTheme.day)



    }else {

        ThemeManager.applyTheme(theme: ColorTheme.night)



    }



}

This codes works in ViewController to change view background color when I switch but the application must be restarted for the UITabBar color to change. Colors doesn't change at the same time like I defined in ViewControllers. ViewController Example;

override func viewWillAppear(_ animated: Bool) {

    self.view.backgroundColor = ThemeManager.currentTheme().mainColor

}

How can solve this problem? What is the correct approach?

Take a look at the documentation of UIAppearance, there is a note that says:

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.

So your tab bar color will not get changed if you set it through its appearance proxy because it's already in the view hierarchy. You need to set it directly:

tabBar.tintColor = ThemeManager.currentTheme().mainColor

Don't use UITabBar.appearance() without didFinishLaunchingWithOptions.
You check to the app has tabBarController, then change this tabBarController.tabBar color.

static func applyTheme(theme:ColorTheme){



    UserDefaults.standard.set(theme.rawValue, forKey: selectedThemeKey)

    UserDefaults.standard.synchronize()

    guard let tabBar = tabBarController?.tabBar else { return }

    tabBar.barTintColor = currentTheme().mainColor }

}