Get index of component selected in UIPickerView Xcode Swift

Question

please forgive my ignorance. I am learning from near scratch.

I'm trying to populate multiple pickerView instances based on the selection of a pickerView at the top of the view. I want the choices shown in the remaining pickerviews to depend on what item has been selected in the first pickerview.

I have 6 pickerViews in total. the 1st makes the general selection I want to base the remainder on.

Pickerview1 has 4 components. If the user selects component 4, all remaining pickerViews to show choices. If the user selects component 2 or 3, I want pickerView 4 and 5 to display N/A while the others show choices. If the user selects component 1, I want pickerViews 3-5 to display N/A while 1-2 show choices.

I assume to do this, I would need the index value of the selected component in pickerView1 to make an if else statement for the func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent etc.

I found selectedRow(inComponent:) in the documentation but have not been able to find working examples of how to implement it in my case.

Attached are some snips of my code so far: import UIKit

class FirstViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource { func numberOfComponents(in pickerView: UIPickerView) -> Int { return 1 }

    var capacities = ["6","9","12","15","18","24"]
    var notUsed = "N/A"
    var oduList = ["MXZ-2C20", "MXZ-3C24", "MXZ-3C30", "MXZ-5C42"]
    var result:Float = 0.0
    var one4num:Float = 1.0
    var factor:Float = 1.08
    var per5ft:Float = 5
    var factory:Float = 98

    var selectedRow = 1

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        selectedRow = pickerView.selectedRow(inComponent: index)
        if pickerView == oduPicker {
            return oduList.count
        }
        else if pickerView == idu1PickerView {
            return capacities.count
        }
        else if pickerView == idu2PickerView {
            return capacities.count
        }
        else if pickerView == idu3PickerView {
            return capacities.count
        }
        else if pickerView == idu4PickerView {
            return capacities.count
        }
        else {
            return capacities.count
        }
    }
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if pickerView == oduPicker {
            return oduList[row]
        }
        else if pickerView == idu1PickerView {
            return capacities[row]
        }
        else if pickerView == idu2PickerView {
            return capacities[row]
        }
        else {
            return capacities[row]
        }
    }
    @IBOutlet weak var oduPicker: UIPickerView!

    @IBOutlet weak var idu1PickerView: UIPickerView!
    @IBOutlet weak var idu2PickerView: UIPickerView!
    @IBOutlet weak var idu3PickerView: UIPickerView!
    @IBOutlet weak var idu4PickerView: UIPickerView!
    @IBOutlet weak var idu5PickerView: UIPickerView!

    @IBOutlet weak var one4Label: UILabel!
    @IBOutlet weak var one4Slider: UISlider!



    @IBOutlet weak var output: UILabel!




    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.oduPicker.delegate = self
        self.oduPicker.dataSource = self
        self.idu1PickerView.delegate = self
        self.idu1PickerView.dataSource = self
        self.idu2PickerView.delegate = self
        self.idu2PickerView.dataSource = self
        self.idu3PickerView.delegate = self
        self.idu3PickerView.dataSource = self
    }

    @IBAction func one4Slider(_ sender: Any) {
        one4Label.text = "\(one4Slider.value)"
    }
    @IBAction func three8Slider(_ sender: Any) {
        three8Label.text = "\(three8Slider.value)"


    }
    @IBAction func calculateButton(_ sender: Any) {
        result = factor*(one4num-factory)/per5ft
        output.text = "\(result)"
    }
}

If I implement the suggestion this way:

import UIKit

class FirstViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

var capacities = ["6","9","12","15","18","24"]
var notUsed = ["N/A"]
var oduList = ["MXZ-2C20", "MXZ-3C24", "MXZ-3C30", "MXZ-5C42"]
var result:Float = 0.0
var one4num:Float = 1.0
var factor:Float = 1.08
var per5ft:Float = 5
var factory:Float = 98

var rowSelected: Int?


func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == oduPicker{
        self.rowSelected = row
        // make anything
    }

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

    if pickerView == oduPicker {
        return oduList.count
    }
    else if pickerView == idu1PickerView {
        return capacities.count
    }
    else if pickerView == idu2PickerView {

        return capacities.count
    }
    else if pickerView == idu3PickerView {
        if rowSelected!  < 2 {
            return 1
        }
        else {
            return capacities.count
        }
    }
    else if pickerView == idu4PickerView {
        if rowSelected! < 3 {
            return 1
        }
        else {
            return capacities.count
        }
    }
    else {
        if rowSelected! < 4 {
            return 1
        }
        else {
            return capacities.count
        }
    }
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if pickerView == oduPicker {
        return oduList[row]
    }
    else if pickerView == idu1PickerView {
        return capacities[row]
    }
    else if pickerView == idu2PickerView {
        return capacities[row]
    }
    else if pickerView == idu3PickerView {
        if rowSelected! < 2 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else if pickerView == idu4PickerView {
        if rowSelected! < 3 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else if pickerView == idu5PickerView {
        if rowSelected! < 4 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else {
        return capacities[row]
    }
}



@IBOutlet weak var oduPicker: UIPickerView!

@IBOutlet weak var idu1PickerView: UIPickerView!
@IBOutlet weak var idu2PickerView: UIPickerView!
@IBOutlet weak var idu3PickerView: UIPickerView!
@IBOutlet weak var idu4PickerView: UIPickerView!
@IBOutlet weak var idu5PickerView: UIPickerView!

@IBOutlet weak var one4Label: UILabel!
@IBOutlet weak var one4Slider: UISlider!



@IBOutlet weak var output: UILabel!




override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.oduPicker.delegate = self
    self.oduPicker.dataSource = self
    self.idu1PickerView.delegate = self
    self.idu1PickerView.dataSource = self
    self.idu2PickerView.delegate = self
    self.idu2PickerView.dataSource = self
    self.idu3PickerView.delegate = self
    self.idu3PickerView.dataSource = self
    self.idu4PickerView.delegate = self
    self.idu4PickerView.dataSource = self
    self.idu5PickerView.delegate = self
    self.idu5PickerView.dataSource = self
}

@IBAction func one4Slider(_ sender: Any) {
    one4Label.text = "\(one4Slider.value)"
}

@IBAction func calculateButton(_ sender: Any) {
    result = factor*(one4num-factory)/per5ft
    output.text = "\(result)"
}
}

The code breaks the "FirstViewController" and seems to invalidate the "numberOfRows" and "titleForRows" statements as well as a cascade of errors below that.

If i implement after those two functions:

 else {
        return capacities[row]
    }
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == oduPicker{
        self.rowSelected = row
        // make anything
    }



@IBOutlet weak var oduPicker: UIPickerView!

@IBOutlet weak var idu1PickerView: UIPickerView!
@IBOutlet weak var idu2PickerView: UIPickerView!
@IBOutlet weak var idu3PickerView: UIPickerView!
@IBOutlet weak var idu4PickerView: UIPickerView!
@IBOutlet weak var idu5PickerView: UIPickerView!

It breaks all the pickerView variables like oduPicker etc.

If I try to bring the statement into the 1st function as such:

var rowSelected: Int?



    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, numberOfRowsInComponent component: Int) -> Int {

    if pickerView == oduPicker {
        self.rowSelected = row
        return oduList.count
    }
    else if pickerView == idu1PickerView {
        return capacities.count
    }...

It again breaks the "FirstViewController" with the error "Type 'FirstViewController' does not conform to protocol 'UIPickerViewDataSource'"

I'm also forced to put a "!" after "rowSelected" for wrapping/unwrapping. I'm not sure if what this means or if it's important at the moment.

Update:

If I implement per Samuel's suggestion as such:

import UIKit

class FirstViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource { func numberOfComponents(in pickerView: UIPickerView) -> Int { return 1 }

var capacities = ["6","9","12","15","18","24"]
var notUsed = ["N/A"]
var oduList = ["MXZ-2C20", "MXZ-3C24", "MXZ-3C30", "MXZ-5C42"]
var result:Float = 0.0
var one4num:Float = 1.0
var factor:Float = 1.08
var per5ft:Float = 5
var factory:Float = 98

var selectedRow = 1



func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    selectedRow = pickerView.selectedRow(inComponent: index)
    if pickerView == oduPicker {
        return oduList.count
    }
    else if pickerView == idu1PickerView {
        return capacities.count
    }
    else if pickerView == idu2PickerView {

        return capacities.count
    }
    else if pickerView == idu3PickerView {
        if selectedRow  < 2 {
            return 1
        }
        else {
            return capacities.count
        }
    }
    else if pickerView == idu4PickerView {
        if selectedRow < 3 {
            return 1
        }
        else {
            return capacities.count
        }
    }
    else {
        if selectedRow < 4 {
            return 1
        }
        else {
            return capacities.count
        }
    }
}
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if pickerView == oduPicker {
        return oduList[row]
    }
    else if pickerView == idu1PickerView {
        return capacities[row]
    }
    else if pickerView == idu2PickerView {
        return capacities[row]
    }
    else if pickerView == idu3PickerView {
        if selectedRow < 2 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else if pickerView == idu4PickerView {
        if selectedRow < 3 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else if pickerView == idu5PickerView {
        if selectedRow < 4 {
            return notUsed[row]
        }
        else {
            return capacities[row]
        }
    }
    else {
        return capacities[row]
    }
}




@IBOutlet weak var oduPicker: UIPickerView!

@IBOutlet weak var idu1PickerView: UIPickerView!
@IBOutlet weak var idu2PickerView: UIPickerView!
@IBOutlet weak var idu3PickerView: UIPickerView!
@IBOutlet weak var idu4PickerView: UIPickerView!
@IBOutlet weak var idu5PickerView: UIPickerView!

@IBOutlet weak var one4Label: UILabel!
@IBOutlet weak var one4Slider: UISlider!



@IBOutlet weak var output: UILabel!




override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    self.oduPicker.delegate = self
    self.oduPicker.dataSource = self
    self.idu1PickerView.delegate = self
    self.idu1PickerView.dataSource = self
    self.idu2PickerView.delegate = self
    self.idu2PickerView.dataSource = self
    self.idu3PickerView.delegate = self
    self.idu3PickerView.dataSource = self
    self.idu4PickerView.delegate = self
    self.idu4PickerView.dataSource = self
    self.idu5PickerView.delegate = self
    self.idu5PickerView.dataSource = self
}

@IBAction func one4Slider(_ sender: Any) {
    one4Label.text = "\(one4Slider.value)"
}

@IBAction func calculateButton(_ sender: Any) {
    result = factor*(one4num-factory)/per5ft
    output.text = "\(result)"
}

}

I get an error after the line:

selectedRow = pickerView.selectedRow(inComponent: index)

"Cannot convert value of type '(Any) -> Int' to expected argument type 'Int'"

See UIPickerViewDelegate and its methods.

rmaddy
– rmaddy

2018-10-24 16:14:11 +00:00
Commented Oct 24, 2018 at 16:14 — rmaddy
– rmaddy, Commented Oct 24, 2018 at 16:14

Augusto · Accepted Answer · 2018-10-24 16:42:25Z

1

You can use the delegate's methods. The method below can help you. The row parameter specific the row selected by user. You can try:

var rowSelected : Int?

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == idu1PickerView {
       self.rowSelected = row
       // make anything
    }
    ...
}

If you have just one component you can use the method like you wrote:

var selectedRow = pickerView.selectedRow(inComponent: 0)

answered Oct 24, 2018 at 16:42

Augusto

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3 Comments

Jeff Over a year ago

See "answer" for further issues using option 1.

Augusto Over a year ago

Sorry, I don't got it/

Jeff Over a year ago

took me a while to type it

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