I would like to be able to input text in either Left-to-Right and Right-to-Left languages into a UISearchBar. This means that once a user has started inputing text in right to left languages, I would like the text alignment to be to the right and vice versa.
The question is - Is there any way to catch these events of language switching? Thanks for your help.
Yes there is. You want to subscribe to UITextInputCurrentInputModeDidChangeNotification. See the UITextInputMode Class Reference.
Use this code in ViewDidLoad
searchbar.semanticContentAttribute = .forceRightToLeft
来源：https://stackoverflow.com/questions/9251592/how-to-change-the-alignment-of-a-uisearchbar-according-to-the-input-language