ios - Does not conform to protocol UIPickerViewDataSource -

i don't know what's wrong coding. tried follow tutorial same error happen.

error:

type 'fourthviewcontroller' not conform protocol 'uipickerviewdatasource'

here code:

import uikit  let characters = ["jaja bink", "luke", "han solo", "princess leia"];  let weapons = ["lightsaber", "pistol", "keris"];  class fourthviewcontroller: uiviewcontroller, uipickerviewdatasource, uipickerviewdelegate {      @iboutlet weak var doublepicker: uipickerview!      override func viewdidload() {         super.viewdidload()          // additional setup after loading view.     }      override func didreceivememorywarning() {         super.didreceivememorywarning()         // dispose of resources can recreated.     }      func numberofcomponentsinpickerview(pickerview: uipickerview) -> int {         return 2     }       func pickerview(pickerview: uipickerview,                     titleforrow row: int,                                 forcomponent component: int) -> string? {          if component == 0 {             return characters[row]         } else {             return weapons[row]         }      }      func pickerview(pickerview: uipickerview, numberofrowsincomponent component: int) -> int? {         if component == 0 {             return characters.count         } else {             return weapons.count         }     }  } 

replacing deprecated version of method of protocol uipickerviewdatasource, if you're using swift 3 works you.

deprecated method of protocol

func numberofcomponentsinpickerview(pickerview: uipickerview) -> int {     return 1 } 

latest method of protocol in swift 3

func numberofcomponents(in pickerview: uipickerview) -> int {     return 1 } 

note: same true other required protocol methods. i.e

deprecated:

func pickerview(pickerview: uipickerview!, numberofrowsincomponent component: int) -> int

recent version:

func pickerview(_ pickerview: uipickerview, numberofrowsincomponent component: int) -> int