Easily add async state tracking to your UITableView data sources

TableState.swift

protocol TableValuable {
    associatedtype TableItem
    static func loadingValue() -> TableItem
    static func failedValue() -> TableItem
    func value() -> TableItem
}

enum TableState<T: TableValuable> {
    case Loading
    case Failed
    case Items([T])

    var count: Int {
        switch self {
        case let .Items(items):
            return items.count
        default:
            return 1
        }
    }

    func value(row: Int) -> T.TableItem {
        switch self {
        case .Loading:
            return T.loadingValue()
        case .Failed:
            return T.failedValue()
        case let .Items(items):
            let item = items[row]
            return item.value()
        }
    }
}

// conforming to the TableValuable protocol

extension String: TableValuable {
    typealias TableItem = String

    static func failedValue() -> TableItem {
        return "Failed..."
    }

    static func loadingValue() -> TableItem {
        return "Loading..."
    }

    func value() -> TableItem {
        return self
    }
}