ios - Dynamically Calculate Pace in Swift -

i have code below. how dynamically calculate pace fill in fields instead of having calculate manually tapping on calculate pace button?

import uikit  class viewcontroller: uiviewcontroller {      @iboutlet weak var mintextfield: uitextfield!     @iboutlet weak var sectextfield: uitextfield!     @iboutlet weak var disttextfield: uitextfield!     @iboutlet weak var pacelabel: uilabel!       func paceinseconds (minutes:double, seconds: double, distance: double) -> double {         return ((minutes*60) + seconds) / distance     }       @ibaction func pacecalculator(sender: uibutton) {         var paceminutes = paceinseconds(((mintextfield.text nsstring).doublevalue, seconds: (sectextfield.text nsstring).doublevalue, distance: (disttextfield.text nsstring).doublevalue)) / 60          var roundedpaceminutes = double(floor(paceminutes))         var decimalpaceseconds = paceminutes - roundedpaceminutes         var intpaceminutes = int(floor(roundedpaceminutes))         var paceseconds = int(floor(decimalpaceseconds * 60))         var pacesecondszero = string(format: "%02d", paceseconds)          pacelabel.text = "\(intpaceminutes):\(pacesecondszero)/km"     }     } 

here's storyboard ui:

you can use various functions of uitextfielddelegate protocol. if assign view controller delegate of text field, able act upon changes in text field.

in case, should implement textfield:shouldchangecharactersinrange:replacementstring: function.