How do I use a dictionary to populate a picker view (swift)? - swift

Question

When using a dictionary to populate a UIPickerView in Swift, how do I specify that the key is to be used as the title for row, while the value is used to perform calculations, such as to set the value for selectedPower, below?
If I were using an array of floats, I'd set it up as below, but how do I do it with a dictionary?
class DiagnosticORViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
var selectedPower : Float!
let FitAssessment : [String : Float] = ["0.50 flat" : -0.50, "0.25 flat" : -0.25, "aligned" : 0, "0.25 steep" : 0.25, "0.50 steep" : 0.50]
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return FitAssessment.count
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return "\(FitAssessment[row])"
}
func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int) {
selectedPower = FitAssessment[row]
}

Answer 1

Two separate arrays solves the problem.
class DiagnosticORViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
var selectedPower : Float!
let FitDescription : [String] = ["0.50 flat", "0.25 flat", "aligned", "0.25 steep", "0.50 steep"]
let FitValue : [Float] = [ -0.50, -0.25, 0, 0.25, 0.50]
#IBOutlet weak var fitAssessmentPicker: UIPickerView!
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return FitDescription.count
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return FitDescription[row]
}
func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int) {
selectedPower = FitValue[row]
}

Answer 2

This morning I had a similar issue.
Since I am reading data from data-base, and fill the picker, I also need IDs of such data.
I will paste a very basic code on how to realize your question with a stupid example I came with:
P.S. It might be late for you, but might be useful for someone else.
import UIKit
class selectLanguage: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource
{
var pickerData = [String:Int]()
#IBOutlet weak var pickerControl: UIPickerView!
override func viewDidLoad()
{
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
pickerData["English"] = 0
pickerData["German"] = 1
pickerData["Serbian"] = 2
pickerData["French"] = 3
pickerData["Italian"] = 4
self.pickerControl.delegate = self
self.pickerControl.dataSource = self
}
// Connect data to picker:
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// The number of columns of data
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return 1
}
// The number of rows of data
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return pickerData.count
}
// The data to return for the row and component (column) that's being passed in
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
// builtInCommands[pickerData[row]]
return "\(Array(pickerData.keys)[row])"
}
//Results of selection
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
let key = Array(pickerData.keys)[row]
let value = pickerData[key]
print(">>>Selected Language is: \(key), and its id is : \(value!)")
}
}

Answer 3

Dictionaries are unordered, so it is better to use an Array of named tuples
let FitAssessment:[(myKey: String, myValue: Double)] = [("0.50 flat", -0.50), ("0.25 flat", -0.25), (etc....)]
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return FitAssessment.count
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return FitAssessment[row].myName
}
func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int) {
selectedPower = FitAssessment[row].myValue
}