My code:
let keyboardManager = IQKeyboardManager.sharedManager()
// This has effect, but is depredated
keyboardManager.considerToolbarPreviousNextInViewClass(CardsInfoView.classForCoder())
// Can't add arrow in inner textField
keyboardManager.toolbarPreviousNextAllowedClasses = Set(arrayLiteral: String(CardsInfoView))
keyboardManager.shouldResignOnTouchOutside = true
keyboardManager.enable = true

Your code:
/** Get all UITextField/UITextView siblings of textFieldView. */
private func responderViews()-> [UIView]? {

    var superConsideredView : UIView?
    //If find any consider responderView in it's upper hierarchy then will get deepResponderView.
    for disabledClassString in toolbarPreviousNextAllowedClasses {
        if let disabledClass = NSClassFromString(disabledClassString) {

"NSClassFromString" In apple doc:
Obtains a class by name.
The class object named by aClassName, or nil if no class by that name is currently loaded. If aClassName is nil, returns nil.

And I see disabledClass is always nil cause SpecialView is currently loaded?