How to use multiple UIPickerViews in one view controller - swift

Question

I am trying to set up 2 UIPickerViews in 1 view controller. I have not been able to find resources that solve my problem.
I have tried following the answer from Diavel Rider on How to use 2 UIPickerView's in one View Controller?. I got some errors from that. I have also tried adding tags but was not able to successfully do that. I am using Swift 4.
Here is the code of my view controller:
import UIKit
class FirstViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ foodTypeUIPickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
var countrows : Int = nutritionPickerData.count
if pickerView == foodTypeUIPickerView { **[Error Here: "Binary operator '==' cannot be applied to operands of type '_' and 'UIPickerView'"]**
countrows = self.foodTypePickerData.count
}
return countrows
}
func pickerView(_ foodTypeUIPickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
if pickerView == nutritionUIPickerView { **[Error Here: "Binary operator '==' cannot be applied to operands of type '_' and 'UIPickerView'"]**
let titleRow = nutritionPickerData[row]
return titleRow
} else if pickerView == foodTypeUIPickerView { **[Error Here: "Binary operator '==' cannot be applied to operands of type '_' and 'UIPickerView'"]**
let titleRow = foodTypePickerData[row]
return titleRow
}
return ""
}
#IBOutlet weak var nutritionUIPickerView: UIPickerView!
#IBOutlet weak var foodTypeUIPickerView: UIPickerView!
var nutritionPickerData = ["Protein", "Fiber", "Iron", "Fat", "Sodium", "Calcium/Vitamin D", "Energy", "Carbohydrates", "Cholestorol"]
var foodTypePickerData = ["Fruits", "Vegetables", "Legumes and Beans", "Grain", "Meat", "Dairy"]
#IBAction func submitUIButton(_ sender: Any) {
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
self.nutritionUIPickerView.delegate = self
self.nutritionUIPickerView.dataSource = self
self.foodTypeUIPickerView.delegate = self
self.foodTypeUIPickerView.dataSource = self
}
}
I need to use 2 picker views in 1 view controller. How do I do this?

Answer 1

You are referencing a non-existent variable named pickerView. You should update the parameter name to pickerView to avoid issues.
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if pickerView == foodTypeUIPickerView {
return self.foodTypePickerData.count
} else {
return self. nutritionPickerData.count
}
}
Make a similar change to the other delegate/data source methods.

Answer 2

You should separate your data sources and delegates and not put them inside your view controller. Set those as the delegate and datasource. Code written in swift 4.2 xcode 10.1
class ViewController: UIViewController {
#IBOutlet weak var foodPicker: UIPickerView!
#IBOutlet weak var nutritionPicker: UIPickerView!
var foodData = FoodData()
var nutritionData = NutritionData()
override func viewDidLoad() {
super.viewDidLoad()
foodPicker.delegate = foodData
foodPicker.dataSource = foodData
nutritionPicker.delegate = nutritionData
nutritionPicker.dataSource = nutritionData
}
#IBAction func actionButton(_ sender: UIButton) {
let food = foodPicker.delegate?.pickerView!(foodPicker, titleForRow: foodPicker.selectedRow(inComponent: 0), forComponent: 0)
let nutrition = nutritionPicker.delegate?.pickerView!(nutritionPicker, titleForRow: nutritionPicker.selectedRow(inComponent: 0), forComponent: 0)
print("You picked: \(food) and \(nutrition)")
}
}
class FoodData: NSObject, UIPickerViewDelegate, UIPickerViewDataSource {
var foodTypePickerData = ["Fruits", "Vegetables", "Legumes and Beans", "Grain", "Meat", "Dairy"]
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return foodTypePickerData.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return foodTypePickerData[row]
}
}
class NutritionData: NSObject, UIPickerViewDataSource, UIPickerViewDelegate {
var nutritionPickerData = ["Protein", "Fiber", "Iron", "Fat", "Sodium", "Calcium/Vitamin D", "Energy", "Carbohydrates", "Cholestorol"]
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return nutritionPickerData.count
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return nutritionPickerData[row]
}
}