URLQueryItem value is optional - ios

Question

Hello I am trying to add queryItems to my URLComponents but because URLQueryItem returns its value as an optional the url keeps having a question mark in it.
var params = ["id":"5"]
let queryParams = toStringDictionary(dictionary: params).map { pair in
return URLQueryItem(name: pair.key, value: pair.value)
}
var components = URLComponents(string: fullURL)
components.queryItems = queryParams
print(components.url)//This is the full url https://demo.com/users/?5
//This https://demo.com/users/?5 should be this https://demo.com/users/5
The question mark is of course resulting in a wrong url. I can't get rid of it.

Answer 1

Query parameters are separated from the rest of the url by a question mark, for example:
https://example.com/path?param_name=param_value
The question mark is not due to an optional, but is the way that query params are supplied.
The example in your comment looks like it has lost the name of the param, I would expect it to read
https://demo.com/users/?id=5
If it definitely doesn't include the id= bit, please could you share the implementation of toStringDictionary so that we can see what's going on there? The dictionary you pass in is already a string dictionary, so seems odd to have such a function.
EDIT: following your clarifications (which have now disappeared, but made it clear that you were looking to add to the path rather than the query string)
It looks like your code is adding query parameters correctly; look closer at the URL it produces, it will be https://demo.com/users/?id=5. Query parameters are not part of the path, they come at the end and are separated from the rest of the URL by a ?
From your edits, it looks as though what you actually want to do is to add to the path of the URL, so that you get https://demo.com/users/5. That URL does not have any query parameters, so URLQueryItem is the wrong tool for the job.
To add to the path, you can do something like the following:
let userID = "5"
let url = URL(string: "https://example.com/users")!
let newUrl = url.appendingPathComponent(userID)
print(newUrl.absoluteString) //https://example.com/users/5
NB - url is only force unwrapped for brevity in the example, since the string passed to URL() is known to be valid. In real use, you should treat the optional more carefully.

Answer 2

There's something wrong with your toStringDictionary
Assuming
let fullURL = "https://demo.com/users/"
all you need to do is…
let queryParams = params.map{ URLQueryItem(name: $0, value: $1) }
var components = URLComponents(string: fullURL)!
components.queryItems = queryParams
print(components.url!)
// https://demo.com/users/?id=5
Note that you should avoid the force unwrapping in practice