rx.controlEvent(.editingChanged)

使用rx.controlEvent(.editingChanged)过程中，输入中文, action一直调2次，一定要记得判断textField.markedTextRange == nil

    searchTextField.rx.controlEvent(.editingChanged)
        .subscribeOn(MainScheduler.instance)
        .subscribe(onNext: { [weak self] _ in
           self?.action() 
        })
        .disposed(by: bag)

func action() { }