Notification center - BLOCK

typealias block = () -> ()

class NotificationCenter {
    static let shared = NotificationCenter()
    var map :[String: [(AnyObject, block)]]

    private init(){
        map = [String: [(AnyObject, block)]]()
    }

    func addObserver(_ event: String, _ handle : @escaping block, _ target: AnyObject){
        let pair = (target, handle)
        map[event, default:[(AnyObject, block)]()].append(pair)
    }

    func postEvent(_ event: String){
        if let list = map[event]{
            for pair in list {
                pair.1()
            }
        }
    }

    func removeObserver(_ event: String, _ target: AnyObject) {
        if let list = map[event]{
            map[event] = list.filter{  $0.0 !== target}
        }
    }

}
class obj {
}


let o1 = obj()
let o2 = obj()

NotificationCenter.shared.addObserver("event1", {
    print("obj1 - event 1")
}, o1)

NotificationCenter.shared.addObserver("event1", {
    print("obj2 - event 1")
}, o2)

NotificationCenter.shared.addObserver("event2", {
    print("obj2 - event 2")
}, o2)


NotificationCenter.shared.postEvent("event1")
NotificationCenter.shared.postEvent("event2")
print()
NotificationCenter.shared.removeObserver("event1", o1)
NotificationCenter.shared.postEvent("event1")
NotificationCenter.shared.postEvent("event2")