Treat an UIPickerView like a combo/select box - ios

Question

I'm working with XCode 8.2.1, Swift 3 and iOS10.
I've a list of items with the following format:
ID | Name
---------
1 | John
2 | Maria
3 | Peter
4 | Roger
The code looks like this:
var formsList = [1:"John", 2:"Maria", 3:"Peter", 4:"Roger"]
What I want to do is to set that data into an UIPickerView, so when someone chooses for example John, the ID 1 is returned, or if someone chooses Peter, the ID 3 is returned.
I do other stuff once I get that ID, that's why I need it.
Any idea or suggestion on how I can achieve this?
Thanks!

Answer 1

You just need to sort your dictionary by its keys and use it as your picker data source:
let formsList = [1:"John", 2:"Maria", 3:"Peter", 4:"Roger"]
let dataSource = formsList.sorted{$0.key<$1.key}
This way you have all your dictionary names sorted in an array including their IDs. Your picker should look something like this:
class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
#IBOutlet weak var pickerView: UIPickerView!
#IBOutlet weak var label: UILabel!
let formsList = [1:"John", 2:"Maria", 3:"Peter", 4:"Roger"]
var dataSource: [(key: Int, value: String)] = []
override func viewDidLoad() {
super.viewDidLoad()
dataSource = formsList.sorted{$0.key<$1.key}
pickerView.delegate = self
pickerView.dataSource = self
label.text = "id: " + String(dataSource[pickerView.selectedRow(inComponent: 0)].key) + " - " + "name: " + dataSource[pickerView.selectedRow(inComponent: 0)].value
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return dataSource.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return dataSource[row].value
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
label.text = "id: " + String(dataSource[row].key) + " - " + "name: " + dataSource[row].value
}
}
sample

Answer 2

Your approach of using a dictionary of your data structure is problematic. Dictionaries are, by design, unordered.
There are lots of ways to do this. Most involve creating an array of some sort containing items for each entry from which you want the user to pick.
For example, create an array of tuples:
typealias NameTuple = (id: Int, name: String)
var namesArray: [NameTuple]
Feed your picker view with the name field of each entry in your array. When the user selects an item, use the selected index to fetch that tuple and then get the ID.
You could also use an array of structs, or an array of name objects.