iOS 检测键盘布局（例如QWERTY、AZERTY）

Question

I am building a custom suggestion/autocorrection feature in an iOS app. It must detect accidental adjacent keypresses and compare this to a known word list to suggest the word it thinks the user intended to type.

For example, if the custom word list contains cat , dog , monkey , and the user types cst , the app can determine that the most likely word was cat (because s is adjacent to the a key)

This will work on a standard QWERTY keyboard , but what happens if the user is using an AZERTY keyboard?

For the autocorrect/suggest to work reliably, the app must be able to detect the keyboard layout in use.

In iOS, it is possible to obtain aUITextInputMode object from a UITextField . This object has a primaryLanguage (string) property, which will display the locale (eg en-GB ), but this does not contain enough granularity to distinguish between English (Australia) QWERTY and English (Australia) AZERTY . In both cases, the primaryLanguage is en-AU .

Is it possible to detect the keyboard layout in iOS?

Answer 1

I have not been able to find a clean solution to this problem. Maybe this would be worth a TSI ticket to discuss it with Apple employees.

I know that this will not be a satisfying answer, but I would still like to share my thoughts here for future readers:

1. Private API of UITextInputMode :

   textField.textInputMode?.value(forKey: "identifierWithLayouts")

   This will return a string like de_DE@sw=QWERTZ-German;hw=Automatic from which you can infer the keyboard layout.

2. UserDefaults

   UserDefaults.standard.object(forKey: "AppleKeyboards")

   This will return a list of all keyboards that the user has installed. In most cases, this will only be one language (besides the emoji keyboard). For example:

   Optional(<__NSCFArray 0x600003b8e6c0>(en_US@sw=QWERTY;hw=Automatic,emoji@sw=Emoji))

   You could also iterate over UserDefaults.standard.dictionaryRepresentation() and search for QWERTZ/QWERTY/AZERTY within the values.

3. With much manual effort, you could maybe encode UITextInputModes to binary data in all ambiguous cases like en_AU. Something like NSKeyedArchiver.archivedData(withRootObject:textField.textInputMode, requiringSecureCoding: false) can then be used to compare binary encodings of the user's textInputMode at runtime.

Answer 2

I have found this old question that may have a solution for you. No sure it's still working, but it shows in the question how to get the current instaled keyboards, and someone provided a "gray area" solution, as it seems that there is no direct way to achieve what you intend to do. Hope this help.

Answer 3

AppleLanguages object at index 0 is common way to get input language. Instead of trying to determinate which language users are using and default layout, as far I worked with custom keyboard extension, I used one of recommended ways from Apple: use separate keyboard layout for each language. In other way I don't think you will have a stable and productive prediction, auto correct, by the way. As for auto correct I used SymSpell ( https://github.com/AmitBhavsarIphone/SymSpell ) and different dictionaries from https://github.com/wolfgarbe/SymSpell/tree/master/SymSpell.FrequencyDictionary to make my own RealmDb for each language. So far it was a little work to do, but finally my keyboard extension was publisehd in App Store. [Note: I am not related with SynSpell owners or coders] See images