Grid View Model with basic method signature

GridViewModel.swift

import UIKit

class GridViewModel {
    static var itemMargin: CGFloat = 8.0
    var data: [Int] = (1...10).map { $0 }
    
    func cellSize(for frame: CGRect, at indexPath: IndexPath) -> CGSize {
        return CGSize(width: 0, height: 0)
    }
}