import Foundation

let aName = Notification.Name(rawValue: "a")

struct Struct { let id: Int }

let structAsAny1 = Struct(id: 1) as AnyObject
let structAsAny2 = Struct(id: 2) as AnyObject
let structAsAny3 = Struct(id: 3) as AnyObject

NotificationCenter.default.addObserver(forName: aName, object: nil, queue: nil) {
    print("限定しないで受け取った→", $0.userInfo![""]!)
}

NotificationCenter.default.addObserver(forName: aName, object: structAsAny1, queue: nil) {
    print("object: Struct(id: 1) で受け取った→", $0.userInfo![""]!)
}

NotificationCenter.default.post(name: aName, object: structAsAny1, userInfo: ["": structAsAny1])
//限定しないで受け取った→ Struct(id: 1)
//object: Struct(id: 1) で受け取った→ Struct(id: 1)
NotificationCenter.default.post(name: aName, object: structAsAny2, userInfo: ["": structAsAny2])
//限定しないで受け取った→ Struct(id: 2)
NotificationCenter.default.post(name: aName, object: structAsAny3, userInfo: ["": structAsAny3])
//限定しないで受け取った→ Struct(id: 3)