EasyFocus

================

A generic way to implement focus on an Identifiable datamodel and makes it simple to get and set focus to records in an array, which is especially useful for Lists.

Why does this package exist ?

Using the out of the box @FocusState propery wrapper over data arrays means using enums with associated values, and the code then becomes somewhat complex as we will see in two trivial examples below.

@FocusState example:

In order to print the text value from a record in yourDataArray, you would need code such as that below.

    public enum FocusID : Hashable {
       case focusID(id: String)
    }
    ...
    @FocusState private var focusedID: FocusID?
    ...
    case .focusID(let id) = focusedID
    if let id = id,
        let index = yourDataArray.firstIndexOf( where { $0.id = id }) {
          print(yourDataArray[index].text)
    } else {
        print("no text")
    }  

Conversely, to set the focus to the row YourDataRow, you have to use syntax similar to

    focusedID = .focusID(id: YourDataRow.id)

It’s fine. It’s okay. It is though a little tedious and non intuitive. It should be easier!

A Solution

This package aims to make it simpler to both set the focus, and get data from the record that is currently focused. Using the same examples as those above, this package eliminates the need to define an enum, and uses your data model as the target of an @Focus property wrapper;

@Focus example:

    @Focus private var focusedRow: YourDataModel?
    ...
    print(focusedRow?.text ?? "no text")

and to set the focus to a data record;

    focusedRow = YourDataRow

Now that’s a lot less code! ( I have omitted some code for brevity, but not much, and no more than is required for the out of the box SwiftUI solution.) See the example.swift file for a full worked example, that syncs it’s focused row in a List with a view model.

Usage

First, import EasyFocus.

Second, define your data model, and make it comply with FocusableListRow To do that, just add an id field, and make sure the struct is hashable. e.g.

    struct myDataModel : FocusableListRow {
        id: Int
        text: String
    }

Then, define your variable to hold focus;

    @Focus private var focusedRow: YourDataModel?

On the data items that you want to set focus, add a call to .enableFocus e.g.

    .enableFocus(on: myDataItem, with: _focusedRow)

you can now set and get focus using the variable focusedRow.

The End.