访问结构中的数据以在 NSTableView 中使用

Question

I'm pretty new to programming and I've been stuck on this for some time. I have a struct called Patient which is full of vars, eg var FIRST: String.

I've already written the code to retrieve data from JSON and populate this struct. It works fine, I can call print(Patient) and I see all the data in the console.

The instance of the struct is a 2d array so when I print to the console I get Patient(FIRST: "Bob", LAST: "Smith") Patient(FIRST: "Dave", LAST: "Evans") Patient(FIRST: "Liz", LAST: "Taylor")

The first tableview method works fine and returns a count of 3.

The second is where I'm stuck:

I declared:

static var globalPatientInstance: [Patient] = []

This is then populated with data from a completion handler. Here's the second method:

extension ViewController: NSTableViewDelegate {

func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {

    let item = ViewController.globalPatientInstance[row]

    let cell = tableView.makeView(withIdentifier: (tableColumn!.identifier), owner: self) as? NSTableCellView

    cell?.textField?.stringValue = item[(tableColumn?.identifier)!]!

    return cell!
}
}  

This gives "Type 'Patient' has no subscript members"

However if I change the line to be:

cell?.textField?.stringValue = item.FIRST

The code will run and I get three rows in the table view with each row having a different name - Bob, Dave, Liz.

What is the correct way to get the rest of the data, ie item.LAST to display also?

Thanks for any help, I've tried so many different things but I'm just really stuck on this.

Answer 1

"Type 'Patient' has no subscript members" - This error is because you are trying to access Patient as an array. Item is a struct, not an array.

When you say your struct is a 2D array, that doesn't make sense. Your struct is a struct. Your "2D" array is just a global instance variable array of structs. [Patient] is a 1D array.

let item = ViewController.globalPatientInstance[row] // item is now a Patient struct
let cell = tableView.makeView(withIdentifier: (tableColumn!.identifier), owner: self) as? NSTableCellView

cell?.textField?.stringValue = item[(tableColumn?.identifier)!]! // This doesn't work because Patient is not an array, but a struct
cell?.textField?.stringValue = item.FIRST // This works because you are accessing the property of item
cell?.textField?.stringValue = item.LAST // This is to display the LAST property of item

return cell!

}

Note -- Please name your class properties camelCase.. You can use this styleguide as a newbie reference..

https://github.com/raywenderlich/swift-style-guide

Also -- using first and last are bad naming conventions for a property because it sounds like first is the first element of an array. I would recommend firstName and lastName.

Answer 2

I figured it out. Thanks for your help guys. This method does what I need:

extension ViewController: NSTableViewDelegate {

fileprivate enum CellIdentifiers {
    static let firstName = "FIRST"
    static let lastName = "LAST"
}

func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {

    var cellValue: String = ""
    var cellIdentifier: String = ""

    let item = ViewController.globalPatientInstance[row]

    if tableColumn == tableView.tableColumns[0] {
        cellValue = item.FIRST
        cellIdentifier = CellIdentifiers.firstName
    }

    else if tableColumn == tableView.tableColumns[1] {
        cellValue = item.LAST
        cellIdentifier = CellIdentifiers.lastName
    }

    if let cell = tableView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: cellIdentifier), owner: nil) as? NSTableCellView {

        cell.textField?.stringValue = cellValue
        //cell.textField?.stringValue = lastName
        return cell
    }
    return nil
}
}