Illegal NSComboBox Data source Swift 5 Storyboard

Question

Created Feb ’23

Replies 2

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Participants 2

I have a combobox in a View Controller that I am trying to populate using an enum. I did some research and think I've done it correct but whenever the view controller launches, I get an error Illegal NSComboBox data source. I thought it may be an issue with the ComboBox (It was copied from another one in the View Controller) so I tried creating one from scratch but I am getting the same thing. I can populate the ComboBox using the addItem no problem. The Combobox does have Use Data Source selected in the Storyboard. Here is my code;

enum Server_Locations: String, CaseIterable {
  case us = "United States"
  case canada = "Canada"
  case other = "Other"
}

class PreferenceController: BaseVC, NSComboBoxDelegate, NSComboBoxDataSource {
@IBOutlet weak var countryComboBox: NSComboBox!

override func viewDidLoad() {
    super.viewDidLoad()

    countryComboBox.dataSource = self
    countryComboBox.delegate = self
    numberOfItemsInComboBoxCell(aComboBox: countryComboBox)
    comboBoxCell(aComboBox: countryComboBox, objectValueForItemAtIndex: 0)
}

func numberOfItemsInComboBoxCell(aComboBox: NSComboBox) -> Int {
    return Server_Locations.allCases.count
  }

func comboBoxCell(aComboBox: NSComboBox, objectValueForItemAtIndex index: Int) -> AnyObject {
    return Server_Locations.allCases[index].rawValue as AnyObject
  }

It seems pretty straightforward but I'm obviously doing something wrong? I think the issue is in the calls to numberOfItemsInComboBoxCell and comboBoxCell I've checked some examples online and they have referencing outlets to the delegate and the dataSource but I am defining them in the viewDidLoad(). I'm using Swift 5 in Storyboard mode with XCode 14.2

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Answer 1

RyanHG OP

Feb ’23

I knew I should have held off a few more minutes. I was able to get this working. My issue was that my function calls for numberOfItemsInComboCell and comboBoxCell were wrong. I fixed it by changing those two calls to;

   func numberOfItems(in comboBox: NSComboBox) -> Int {
   return Server_Locations.allCases.count
  }

and

   func comboBox(_ comboBox: NSComboBox, objectValueForItemAt index: Int) -> Any? {
    return String(KeyboardHotKeys.allCases[index].rawValue) as AnyObject
  }

so

    numberOfItems(in: countryComboBox)
    comboBox(countryComboBox, objectValueForItemAt: 0)

It is now complaining that I am not using the result of the call. Should I bother assigning the result to an empty value (ie: _ =) or is there something else I should be doing with it? The data is populating the NSComboBox as expected.

0

Answer 2

Claude31 OP

Feb ’23

If you set Use Data Source selected in the Storyboard, why not set delegate and dataSource there as well ?

What is the use of numberOfItemsInComboBoxCell ? You call it but do nothing with the result.

You should instead implement the dataSource functions:

func numberOfItems(in: NSComboBox) -> Int {
   Server_Locations.allCases.count
}

And also

func comboBox(NSComboBox, objectValueForItemAt: Int) -> Any? {
    Server_Locations.allCases[index].rawValue as Any
}

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