Here you can create a Dictionary key can hold any kind of object or value or enum. Here, DataSourceType.dictionary key is Generic.

KeyAsGeneric.Swift

import UIKit
import Foundation

enum Gender:Int {
    case male,female,other
}

class Department:Hashable,Equatable{
    var uid: Int
    var hashValue: Int {
        return self.uid
    }
    
    init(uid: Int) {
        self.uid = uid
    }

    public static func ==(lhs: Department, rhs: Department) -> Bool {
        return lhs.uid == rhs.uid
    }
}

class People {}

class DataSourceType<T:Hashable> {
    var dictionary:[T:[People]]?
    init() {
        dictionary = [:]
    }
}

var datasource:Any? = nil
datasource = DataSourceType<Department>()
var ds = datasource as! DataSourceType<Department>
let d = Department.init(uid: 121)
ds.dictionary?[d] = [People()]


datasource = DataSourceType<Gender>()
var genderSource = datasource as! DataSourceType<Gender>
genderSource.dictionary?[.male] = [People()]