Datepicker working with the object

Hi all, I have a Date Picker in my test app. When I link it into my ViewController class (using the assistant editor) it appears as a function and allows me to react to changes received from the date picker - all good. However, I want to create buttons to increment and decrement the date and update the date picker accordingly (the app needs to allow the user to set a date any time in 3 years and then to quickly flick through the days either side of the selected date, I want the date picker to be updated to show the new date as adjusted by the buttons and to execute the code associated with the change to the date). My question is how do I configure the code in the buttons to modify the date picker object, given that it only appears as a function in the class, not an explicit object with properties.