Swift code for iOS app

//
//  ViewController.swift
//  Mean, Mode, Median
//
//  Created by Jonathan Valldejuli on 6/29/15.
//  Copyright (c) 2015 Randomware. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    //outlets for ui
    @IBOutlet weak var undoBtn: UIButton!

    @IBOutlet weak var listField: UITextField!

    @IBOutlet weak var enterBtn: UIButton!

    @IBOutlet weak var calcMeanBtn: UIButton!

    @IBOutlet weak var meanLabel: UILabel!

    @IBOutlet weak var calcMedianBtn: UIButton!

    @IBOutlet weak var medianLabel: UILabel!

    @IBOutlet weak var calcModeBtn: UIButton!

    @IBOutlet weak var modeLabel: UILabel!

    @IBOutlet weak var numbersList: UILabel!


    //vars for use
    var userList: [Double] = []

    var stringForListLabel: String = ""




    //math functions TAKE DOUBLE LIST RETURN DOUBLE/DOUBLE LIST
    func average(numbers: [Double]) -> Double {

        var total = 0.0

        for x in numbers {

            total += x

        }

        return total/Double(numbers.count)


    }


    func median(var numbers: [Double]) -> Double {

        numbers = sorted(numbers)

        if numbers.count % 2 == 0 {

            return Double((numbers[numbers.count/2] + numbers[numbers.count/2 - 1])/2.0)

        }

        else {

            return Double(numbers[numbers.count/2])

        }

    }


    //set a variable equal to the result of the call then use varname.mainReturn or varname.exists to get tuple value
    func mode(numbers: [Double]) -> (mainReturn: [Double], exists: Bool) {

        var occurences = [Double:Int]()

        var signal: Bool

        var mode = [Double]()

        var max = 0

        for number in numbers {

            if var test = occurences[number] {

                occurences[number] = occurences[number]! + 1

            }

            else {

                occurences[number] = 1

            }

        }

        for (key, item) in occurences {

            switch item {

            case max:

                let d = "d"

            case let x where x > max:

                max = x

            default:

                let a = "a"

            }

        }

        for (key, item) in occurences {

            if item == max {

                mode.append(key)

            }

        }

        if max == 1 {

            signal = false

        }

        else {

            signal = true

        }

        return (mode, signal)

    }







    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }







    @IBAction func enterBtnTapped(sender: UIButton) {

        if stringForListLabel == "Numbers" {

            stringForListLabel = ""

        }

        var numberToAdd: Double = (listField.text as NSString).doubleValue

        userList.append(numberToAdd)

        var numberToAddToLabel = listField.text

        if userList.count == 1 {

            stringForListLabel += numberToAddToLabel

        }

        else {

            stringForListLabel += ", " + numberToAddToLabel

        }

        numbersList.text = stringForListLabel

        listField.text = ""

    }


    @IBAction func undoBtnTapped(sender: UIButton) {

        userList.removeAtIndex(userList.count - 1)

        stringForListLabel = ""

        if userList.count != 0 {

            stringForListLabel += userList[0].description

            for x in 1..<userList.count {

                stringForListLabel += ", " + userList[x].description

            }

        }

        else {

            stringForListLabel = "Numbers"

        }

        numbersList.text = stringForListLabel




    }

    @IBAction func calcBtnTapped(sender: UIButton) {

        switch sender.tag {

        case 1:

            meanLabel.text = average(userList).description

        case 3:

            var optionalMode = mode(userList)

            if optionalMode.exists {

                var ourStr = ""

                for mode in optionalMode.mainReturn {

                    ourStr += mode.description

                }

                modeLabel.text = ourStr

            }

            else {

                modeLabel.text = "No Mode"

            }

        case 2:

            medianLabel.text = median(userList).description

        default:

            var done = "Done! :)"





        }





    }








}