Very basic implementaion of `lodash.get`. Not meant for production, just a proof

get.swift

protocol KeyValuePathing {
    subscript(keyPathWithString keyPath: String) -> Any? { get }
}

extension Array: KeyValuePathing {
    subscript(keyPathWithString keyPath: String) -> Any? {
        get {
            var parts = keyPath.components(separatedBy: ".")
            let initialKey = parts.removeFirst()

            guard let index = Int(initialKey), self.count - 1 > index else {
                return nil
            }

            if let value = self[index] as? KeyValuePathing {
                return value[keyPathWithString: parts.joined(separator: ".")]
            }

            return self[index]
        }
    }
}

extension Dictionary: KeyValuePathing {

    private func _defaultKeyPath(keyPath: Key) -> Any? {
        return self[keyPath]
    }

    subscript(keyPathWithString keyPath: String) -> Any? {
        get {
            var parts = keyPath.components(separatedBy: ".")
            let initialKey = parts.removeFirst()

            if let value = self._defaultKeyPath(keyPath: initialKey as! Key) as? KeyValuePathing {
                return value[keyPathWithString: parts.joined(separator: ".")]
            } else if let key = initialKey as? Key, let value = self._defaultKeyPath(keyPath: key) {
                return value
            }

            return nil
        }
    }
}

func get<Key: Hashable, Value>(_ keyPath: String, in object: Dictionary<Key, Value>, withDefaultValue defaultValue: Any? = nil) -> Any? {
    return object[keyPathWithString: keyPath] ?? defaultValue ?? nil
}