How do you budget an APNs payload: bytes versus characters, escaped slashes, and what belongs in it?

Predict first

How big are these payloads?

import Foundation
func size(_ o: Any, _ opts: JSONSerialization.WritingOptions = []) -> Int { try! JSONSerialization.data(withJSONObject: o, options: opts).count }
let small: [String: Any] = ["aps": ["alert": ["title": "Score", "body": "Pune 2 - 1 Goa"], "sound": "default", "thread-id": "match-42"], "match": 42]
print("small payload bytes:", size(small))
let text = String(repeating: "é", count: 2100)
let accent: [String: Any] = ["aps": ["alert": text]]
print("characters:", text.count, "utf8 bytes:", text.utf8.count, "payload bytes:", size(accent), "over 4096:", size(accent) > 4096)
let url: [String: Any] = ["aps": ["alert": "x"], "deeplink": "https://bank.example/a/b/c"]
print("with escaped slashes:", size(url), "without:", size(url, [.withoutEscapingSlashes]))
let emoji = "🚀"
print("emoji:", emoji.count, "character,", emoji.utf8.count, "bytes")
let silent: [String: Any] = ["aps": ["content-available": 1]]
print("silent payload:", String(data: try! JSONSerialization.data(withJSONObject: silent), encoding: .utf8)!)
let localized: [String: Any] = ["aps": ["alert": ["title-loc-key": "SCORE_TITLE", "loc-key": "SCORE_BODY", "loc-args": ["Pune", "2", "1"]], "mutable-content": 1, "interruption-level": "time-sensitive", "relevance-score": 0.5]]
let d = try! JSONSerialization.jsonObject(with: JSONSerialization.data(withJSONObject: localized)) as! [String: Any]
print("keys:", (d["aps"] as! [String: Any]).keys.sorted())

• 2100 é characters give 4200 bytes and 4220 payload bytes, over 4096; escaped slashes add bytes
• Characters and bytes are always equal
• Escaping slashes saves bytes