PickerView for multiple text fields is just showing one Array

This is my solution... use an enum to track the selected state and add UITextFieldDelegates:

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource, UITextFieldDelegate {


//Mark: Properties
@IBOutlet weak var genderPicker: UITextField!
@IBOutlet weak var branchePicker: UITextField!
@IBOutlet weak var countryPicker: UITextField!

enum TextFieldType {
    case gender
    case branche
    case country
    case none
}

// Picker View Arrays
let genders = ["male", "female", "non-binary"]
let branches = ["Advertising", "Architecture", "Design: Product", "Design: Graphic", "Design: Fashion", "Design: Others", "Film/ Video & TV", "IT", "Museums & Galleries", "Music", "Photography", "Performing & Visual Arts", "Radio", "Others"]
let countries = ["Austria", "Australia", "USA", "Germany"]

// Picker View
var pickerViewSignUp = UIPickerView()
var selectedPikerType =  TextFieldType.none

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.


    // Pickers

    pickerViewSignUp.delegate = self
    pickerViewSignUp.dataSource = self


    // Delegates
    genderPicker.textAlignment = .center
    genderPicker.inputView = pickerViewSignUp
    genderPicker.placeholder = "Select Gender"
    genderPicker.delegate = self

    branchePicker.textAlignment = .center
    branchePicker.inputView = pickerViewSignUp
    branchePicker.placeholder = "Select Branch"
    branchePicker.delegate = self

    countryPicker.textAlignment = .center
    countryPicker.inputView = pickerViewSignUp
    countryPicker.placeholder = "Select Country"
    countryPicker.delegate = self
}


// Mark: PickerViews
        // List of the SignUp used Drop Down Items

        // TextField delegate


func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {

    switch textField {
    case genderPicker: selectedPikerType    = .gender
    case branchePicker: selectedPikerType   = .branche
    case countryPicker: selectedPikerType   = .country
    default: selectedPikerType              = .none
    }


    pickerViewSignUp.reloadAllComponents()

    return true
}


func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

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

    switch selectedPikerType {
    case .branche   : return branches.count
    case .country   : return countries.count
    case .gender    : return genders.count
    case .none      : return 0
    }

}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

    switch selectedPikerType {
    case .branche   : return branches[row]
    case .country   : return countries[row]
    case .gender    : return genders[row]
    case .none      : return nil
    }
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int)  {

    switch selectedPikerType {
    case .branche   : branchePicker.text = branches[row]
    case .country   : countryPicker.text = countries[row]
    case .gender    : genderPicker.text = genders[row]
    case .none      : break
    }
}

}

I'd also suggest you a better naming of the variables... If the object is a textfield use the prefix "txt" ... so txtGender and so on. It is way clearer. Use also extensions to split datasources and delegates it makes it all more readable. :)

You can write an extension like this:

extension ViewController: UITextFieldDelegate {

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {

       switch textField {
       case genderPicker: selectedPikerType    = .gender
       case branchePicker: selectedPikerType   = .branche
       case countryPicker: selectedPikerType   = .country
       default: selectedPikerType              = .none
       }


       pickerViewSignUp.reloadAllComponents()

       return true
   }

}

Have a global textField variable in your class to get the instance of textField you are editing and assign the value when editing.

In the pickerView delegate and datasource methods do the comparison between the current textField and the rest of the textField elements. It should work.

Below is the code for your reference:

class SignupViewController {

var currentTextfield: UITextField?

// Mark: PickerViews
// List of the SignUp used Drop Down Items

// TextField delegate

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
    currentTextfield = textField
    pickerViewSignUp.reloadAllComponents()
    return true
}


func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    switch currentTextfield {
    case genderPicker:
        return genders.count
    case branchePicker:
        return branches.count
    default
        return countries.count
    }
}

}