Using Swift's reduce method to construct a URL path with parameters

reduce.txt

let params = [ "userID" : 1, "balance" : 1000 ]

let string: String = params.reduce("") {
    if $0.isEmpty {
        return $1.key + "=" + String($1.value)
    } else {
        return $0 + "&" + $1.key + "=" + String($1.value)
    }
}

print("https://example.com?" + string)
// https://example.com?userID=1&balance=1000