Can the TimedAction library be used to call functions of an object
You can't. The TimedAction class doesn't support the function prototype required for your undefined class (it has to match your class, so can't be written).

You have to call a normal function which then calls the class function, or you have to have your class function as static so it doesn't include the class in the function prototype.

class foo {
    public:
        static void runMe() { 
            // blah blah
        }
};

TimedAction funtionTimed = TimedAction(1000, foo::runMe);


However, TimedAction is pretty simplistic and you don't really need it.  You can just write a function to only run every so often:

class foo {
    private:
        uint32_t _runMeTimestamp;
    public:
        void runMe() {
            if (millis() - _runMeTimestamp &lt; 1000) return;
            _runMeTimestamp = millis();
            // blah blah
        }
};

foo myFoo;

void loop() {
    myFoo.runMe();
}


Those two lines of code, plus a variable to store the timestamp in, are all you need to make a function run at periodic intervals.