How to pass an unknown struct to a function - swift 3, IOS10 - function

Question

This will be my first question on StackOverflow and my first question posed on Swift 3; I'm a beginner and perhaps biting off more than I can chew, however...
I am trying to create a class which will assist in creating menu items (the class is called 'MenuItems') to populate into a dynamic table in my IOS application. I have created the bulk of the class which identifies from the data passed to it what the headers are and how many of each type will be separated into sections within the table. I am now at the stage of trying to make the class more generic so it will work for different data structures that I may want to populate into a similar table in the future.
The data that I wish to have in the table comes from a structure that is in its own swift file. It looks like this:
struct EquipmentStruct {
var name : String!
var serialNumber : String?
var alias : String?
var image : UIImage?
}
I have an array of type EquipmentStruct which, for the short term, is initialised in my tableViewController file (it will not stay here in the future) and I hope to create a public function in my MenuItems class which will allow me to add an item to the table as necessary
func addItem(item, dataType) // types for item and dataType are part of my question
In designing this function I discover my questions:
How do I pass a variable of type EquipmentStruct to an instance of my MenuItems class so I can add it to my table - please note, all I am asking is for guidance on how to complete the addItem method and not the rest of the class. In my mind I want to do something like:
var dataArray : [EquipmentStruct] =
[EquipmentStruct(name: "SA80", serialNumber:"01234-56-789", alias: "29", image: #imageLiteral(resourceName: "SA80")),
EquipmentStruct(name: "LSW", serialNumber:"11111-22-333-4444", alias: "98", image: #imageLiteral(resourceName: "LSW"))]
var tableMenuItems = MenuItems() // create instance of class MenuItems
override func viewDidLoad() {
super.viewDidLoad()
for var itemNumber in 0..<dataArray.count{
tableMenuItems.addItem(item: generalHoldingsDataArray[itemNumber], dataType: EquipmentStruct)
}
The addItems method prototype would therefore be something like:
// Add new item of type 'dataType' to MenuItems.tableDataArray
// Store tableDataArrayType for use throughout the class
//
func addItem(item: [Something], dataType: SomeVariableType){
if let newItem = item as! dataType{ // cast the variable received to its type
tableDataArrayType = dataType
tableDataArray.append(newItem)
}
}
Is this a good way of doing things?
Is there a simpler way of doing what I'm trying to do?
If I continue down this path, what issues might I come up against in the future?
Your assistance would be gratefully appreciated.
Kind regards

Answer 1

A table view is supposed to hold only one type of stuff as model. A single table view is not designed to show info about an EquipmentStruct, a SomeOtherStruct and maybe 3 Foos. You have to generalize all these into one single type.
Another possibility is that you want to create a MenuItems type that can create a table view that shows EquipmentStructs, a table view that shows SomeOtherStructs, basically a table view that shows whatever type you like. If this is the case, you should use generics.
Make the MenuItems class like this:
class MenuItems<T : SomeProtocol> {
var tableDataArray: [T] = []
func addItem(_ newItem: T) {
tableDataArray.append(newItem)
}
// ...
// since you just need guidance on creating addItems method, figure the rest yourself please! XD
}
To create a table view that shows EquipmentStructs,
let tableMenuItems = MenuItems<EquipmentStruct>()
To create a table view that shows SomeOtherStructs,
let tableMenuItems = MenuItems<SomeOtherStruct>()
Notice the SomeProtocol in the first line? That defines what properties/methods a type should have, in order to be shown in a table view. A possible SomeProtocol might be:
protocol SomeProtocol {
var displayTitle: String { get }
var displaySubtitle: String? { get }
var displayImage: UIImage? { get }
}
This just ensures that the type you want to display in the table view have properties called displayTitle, displaySubtitle, displayImage. You can use these properties in your MenuItems class to set the table view cells' appearences.