Change app language in iOS without restarting the app

Question

I have seems some apps can change the language internally within the app without the need of restarting the app, I am wondering how they are implemented.

For example

Answer 1

You need to load another bundle like this(where @"en" could be locale you need):

NSString *path = [[NSBundle mainBundle] pathForResource:@"en" ofType:@"lproj"];
NSBundle *languageBundle = [NSBundle bundleWithPath:path];

and make macros/function like NSLocalizedString which use your loaded bundle or use methods on that bundle directly like this

[languageBundle localizedStringForKey:key value:value table:tableName];

[[NSBundle mainBundle] localizations] lists all app localizations(including "Base").

Also I wrote helper class which does this(note that it has ReactiveCocoa as a dependency). It allows language change without app restart and sends current locale each time it's changed.