Creating Second Delegate - ios

Question

I'm trying to create a second UIPickerView delegate so I can control them individually instead of using if blocks. Below is an example I put together, I'm unsure of how to connect the second UIPickerView outlet to the second UIPickerView delegate (assuming that is all I am missing).
import UIKit
protocol secondDelegate {
func secondPickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
func secondNumberOfComponents(in pickerView: UIPickerView) -> Int
}
protocol secondDelegateDataSource {
func secondPickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?
}
class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource, secondDelegate, secondDelegateDataSource {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
p1.delegate = self
p1.dataSource = self
p2.delegate = self
p2.dataSource = self
}
#IBOutlet weak var p1: UIPickerView!
#IBOutlet weak var p2: UIPickerView!
var delegate2: secondDelegate?
var dataSource2: secondDelegateDataSource?
let picker1 = ["1","3","5"]
let picker2 = ["2","4","6"]
// first picker
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return picker1.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return picker1[row]
}
// second picker
func secondNumberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func secondPickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return picker2.count
}
func secondPickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return picker2[row]
}
}

Answer 1

So here's the problem: you are saying the words "second delegate", but in fact you still have just one delegate — the view controller.
That's your mistake. Make your deeds match your words. Get all the delegate code out of the view controller. Instead, give your view controller two helper objects — the two picker delegates. Route the dataSource and delegate properties of the two pickers correctly, one to each delegate. Now the messages are coming and going to completely separate places, and you will not have any single bottleneck with if clauses everywhere as you do now.
Here's a simplified example where the two helpers are instance of one class — naturally, nothing requires that you do it that way:
class Helper: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
let data: [String]
init(data: [String]) {
self.data = data
}
func numberOfComponents(in pickerView: UIPickerView) -> Int {
1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
data.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
data[row]
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
print(data[row])
}
}
class ViewController: UIViewController {
#IBOutlet weak var p1: UIPickerView!
#IBOutlet weak var p2: UIPickerView!
let helper1 = Helper(data:["Manny", "Moe", "Jack"])
let helper2 = Helper(data:["Harpo", "Chico", "Groucho"])
override func viewDidLoad() {
super.viewDidLoad()
p1.delegate = helper1
p1.dataSource = helper1
p2.delegate = helper2
p2.dataSource = helper2
}
}
If the two picker views do very different kinds of thing, then you would want two separate Helper classes, each of which acts as a picker view delegate in its own way. Again, the goal here is to avoid having to examine the pickerView in the datasource and delegate methods and decide with an if clause what to do; each Helper type would do just one thing.