// traits

protocol TableViewUpdating {
    func update(at: IndexPath)
}

extension TableViewUpdating {
    func update(at indexPath: IndexPath) {
        // default implementation
    }
}

protocol TableViewDeleting {
    func delete(at: IndexPath)
}

extension TableViewDeleting {
    func delete(at indexPath: IndexPath) {
        // default implementation
    }
}


// classes

class DataSourceOne: UITableViewDataSource, TableViewUpdating, TableViewDeleting {

}

class DataSourceTwo: UITableViewDataSource, TableViewUpdating {

}


// test

let one = DataSourceOne()

one.update(at: IndexPath(item: 0, section: 0))
one.delete(at: IndexPath(item: 0, section: 0))

let two = DataSourceTwo()
two.update(at: IndexPath(item: 0, section: 0))
// two.delete(at: IndexPath(item: 0, section: 0)) => error: value of type 'DataSourceTwo' has no member 'delete'