String KeyPath accessor of Dictionary

Dictionary+Extension.swift

import Foundation

// Time Complexity: O(N), N stands for the level of key path
extension Dictionary where Key == String {
    subscript(keyPath keyPath: String) -> Any? {
        get {
            guard !keyPath.isEmpty else { return nil }
            var value: Any? = self
            for key in keyPath.components(separatedBy: ".") {
                if let node = (result as? [Key: Any])?[key] {
                    value = node
                } else {
                    return nil
                }
            }
            return value
        }

        set {
            let paths = keyPath.components(separatedBy: ".")
            guard let first = paths.first else {
                return
            }

            if paths.count == 1, let newValue = newValue as? Value {
                self[first] = newValue
                return
            }

            if var nestedDict = self[first] as? [Key: Any] {
                nestedDict[keyPath: Array(paths.dropFirst()).joined(separator: ".")] = newValue
                self[first] = nestedDict as? Value
            }
        }
    }
}

extension Dictionary where Key == String {
    subscript(string keyPath: String) -> String? {
        get { return self[keyPath: keyPath] as? String }
        set { self[keyPath: keyPath] = newValue }
    }

    subscript(integer keyPath: String) -> Int? {
        get { return self[keyPath: keyPath] as? Int }
        set { self[keyPath: keyPath] = newValue }
    }
}

// Example
var dict: [String: Any] = [
    "batchcomplete": "",
    "continue": [
        "rncontinue": "0.067678657404|0.067678667039|13394072|0",
        "continue": "-||"
    ],
    "query": [
        "random": [
            "id": 34538560,
            "ns": 3,
            "title": "User talk:59.188.42.121"
        ]
    ]
]

dict[keyPath: "query.random.id"] // 34538560, Any?
dict[keyPath: "query.random.title"] // "User talk:59.188.42.121"
dict[string: "query.random.title"]?.append("GG") // // "User talk:59.188.42.121GG"
dict[keyPath: "query.random.id"] = 12345 
dict[integer: "query.random.id"] // 12345