For Android you can use this:
public void showSoftKeyboard(View v) {
Activity activity = (Activity) v.getContext();
InputMethodManager inputMethodManager = (InputMethodManager) activity.getSystemService(Activity.INPUT_METHOD_SERVICE);
inputMethodManager.showSoftInput(activity.getCurrentFocus().getWindowToken(), 0);
}
OR just call:
((InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE)).toggleSoftInput(InputMethodManager.SHOW_FORCED, InputMethodManager.HIDE_IMPLICIT_ONLY);
For iOS I found this one:
$('#element').focus().blur().focus();