알림 userInfo 페이로드

알림 userInfo

userInfo와 함께 게시하기

import Foundation

let center = NotificationCenter.default
let name = Notification.Name("scoreChanged")
center.post(name: name, object: nil, userInfo: ["score": 100])
print("Posted with payload")

userInfo 읽기

import Foundation

let center = NotificationCenter.default
let name = Notification.Name("scoreChanged")
_ = center.addObserver(forName: name, object: nil, queue: nil) { note in
    if let score = note.userInfo?["score"] as? Int {
        print("Score: \(score)")
    }
}
center.post(name: name, object: nil, userInfo: ["score": 42])

여러 값

import Foundation

let center = NotificationCenter.default
let name = Notification.Name("login")
_ = center.addObserver(forName: name, object: nil, queue: nil) { note in
    let user = note.userInfo?["user"] as? String ?? "?"
    let admin = note.userInfo?["admin"] as? Bool ?? false
    print("\(user) admin=\(admin)")
}
center.post(name: name, object: nil, userInfo: ["user": "ada", "admin": true])

타입 안전한 키

import Foundation

enum Keys { static let amount = "amount" }
let center = NotificationCenter.default
let name = Notification.Name("purchase")
center.post(name: name, object: nil, userInfo: [Keys.amount: 9.99])
print("Used a constant key")

신중하게 형 변환하기

import Foundation

let note = Notification(name: Notification.Name("x"), object: nil, userInfo: ["n": "oops"])
if let n = note.userInfo?["n"] as? Int {
    print(n)
} else {
    print("Wrong type, handled safely")
}

전달 데이터로 사용하는 사용자 정의 구조체

import Foundation

struct Event { let id: Int }
let note = Notification(name: Notification.Name("e"), object: nil, userInfo: ["event": Event(id: 7)])
if let e = note.userInfo?["event"] as? Event {
    print("Event id: \(e.id)")
}

게시 동작 감싸기

import Foundation

let name = Notification.Name("progress")
func postProgress(_ value: Int) {
    NotificationCenter.default.post(name: name, object: nil, userInfo: ["value": value])
}
postProgress(75)
print("Posted progress")

읽기 동작 감싸기

import Foundation

extension Notification {
    var progressValue: Int? { userInfo?["value"] as? Int }
}
let n = Notification(name: Notification.Name("progress"), object: nil, userInfo: ["value": 50])
print(n.progressValue ?? -1)

기본값과 누락된 키

import Foundation

let n = Notification(name: Notification.Name("y"), object: nil, userInfo: [:])
let count = n.userInfo?["count"] as? Int ?? 0
print("Count defaulted to \(count)")

전달 데이터는 작게 유지하기

import Foundation

let name = Notification.Name("itemUpdated")
// Send just an id, not a heavy object graph.
NotificationCenter.default.post(name: name, object: nil, userInfo: ["id": 1234])
print("Posted a lightweight payload")

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