Autolayout RTL support in app

Question

I am aware that iOS has the RTL (right to left) support for languages, and that by using leading and trailing constraints I "tell" autolayout to stack the elements according to the language orientation. This all works great. If I want a constraint to be fixed, I turn off respect language direction and there is no problem. However I need to make in app language selection, which will have LTR and RTL languages. How to signal the app to mirror the view to RTL and vice versa? I know this could be done if I would iterate through constraints and change the leading/trailing to left right and vice versa, but is there any simpler solution for that? App restart is also fine if needed! Solution should support iOS 8.x + Thank you

Answer 1

An app restart is required no other solution.

Apple guidlines suggests to the developers not to implement a language selection from inside the app. The developer should use the device selected language.

If you are asking for a way to restart the app. this also not possible. You can show an alert to the user ask him/her to restart. closing the viewcontrollers won't solve the problem either.

I usually do not turn on localisation for my app if I wanna implement an in-app langauge selection. unfortunately, I do all constraints by coding.

You can also have two layouts one for RTL and one for LTR. but, you also need to stop localisation, leading and trailing constraints will rune your layout. or you need to convert them all to left right manually. turning off inter localisation lets any added constraint to have left and right attributes and not trailing and leading.

Answer 2

hasan83 answer is quite helpful still i would like to share what i have done to support both Right-To-Left and Left-To-Right language.

As hasan83 correctly pointed in the answer that 'An app restart is required' in order to change the UI Right-To-Left and Left-To-Right vice-versa.

So if you have to provide in app language selection at any cost, there is a way,

You have to add two storyboard for your app, one is for English and other one is for Arabic (in my case). Design the screen for English language first then copy and paste the same in Arabic language, and change the position of screen to make mirror view of English screen. Thats it for design perspective.

Edit your didFinishLaunchingWithOptions as below,

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

//Load storyboard for the selected language
if ([kGetSelectedLanguage isEqualToString:kEnglish]) { //Load English Storyboard

    // Get English Language Storyboard
    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"English" bundle:nil];

    // Create Navigation controller with RootViewController
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:[storyBoard instantiateViewControllerWithIdentifier:@"FindRestaurantsViewController"]];

    // Set Windows RootViewController
    [self.window setRootViewController: navigationController];

} else { //Load Arabic Storyboard

    // Get Arabic Language Storyboard
    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"Arabic" bundle:nil];

    // Create Navigation controller with RootViewController
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:[storyBoard instantiateViewControllerWithIdentifier:@"FindRestaurantsViewController"]];

    // Set Windows RootViewController
    [self.window setRootViewController: navigationController];

}
}

Add below code to the action of button where user changes the app language,

if ([kGetSelectedLanguage isEqualToString:kEnglish]) { //Load Arabic Storyboard

    // Get Arabic Language Storyboard
    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"Arabic" bundle:nil];

    // Create Navigation controller with RootViewController
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:[storyBoard instantiateViewControllerWithIdentifier:@"YourRootViewControllerIdentifier"]];

    // Set Windows RootViewController
    [appDelegate.window setRootViewController: navigationController];

    [[NSUserDefaults standardUserDefaults] setObject:kArabic forKey:kSelectedLanguage];

    [[NSUserDefaults standardUserDefaults] setObject: @"2" forKey:kSelectedLanguageId];

    [[NSUserDefaults standardUserDefaults] synchronize];

} else { //Load English Storyboard

    // Get English Language Storyboard
    UIStoryboard *storyBoard = [UIStoryboard storyboardWithName:@"English" bundle:nil];

    // Create Navigation controller with RootViewController
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:[storyBoard instantiateViewControllerWithIdentifier:@"YourRootViewControllerIdentifier"]];

    // Set Windows RootViewController
    [appDelegate.window setRootViewController: navigationController];

    [[NSUserDefaults standardUserDefaults] setObject:kEnglish forKey:kSelectedLanguage];

    [[NSUserDefaults standardUserDefaults] setObject: @"1" forKey:kSelectedLanguageId];

    [[NSUserDefaults standardUserDefaults] synchronize];
}

Make sure you add the language change button to the RootViewController, otherwise it will not look good if you allow user to change the language anywhere in between the application flow.