Passing headers to URL with Swift URLSession

Question

I don't feel like sharing the actual link as it may have some private information so don't be surprised if it doesn't work.

I have a link that looks like this: www.somelink.com/stuff/searchmembers?member=John

And some headers that I need to pass, like Login: Admin, Password: Admin

When I use this site everything seems to be working just fine, I put the link, make it GET and put headers in key:value format and as a result I get the list of all members, but how can I do the same with URLSession? Here's what I currently have and I don't get anything at all. What am I doing wrong there?

func getAllMembers(urlString: String) {

    guard let url = URL(string: urlString) else { return }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("Admin", forHTTPHeaderField: "Login")
    request.setValue("Admin", forHTTPHeaderField: "Password")
    request.httpBody = "member=John".data(using: .utf8)!


    URLSession.shared.dataTask(with: request) { (data, response, error) in
        print(response)
        print(data)
    }.resume()
}

`request.httpBody = "member=John".data(using: .utf8)!`, that's not adding it at the end of your URL. I'm not familiar with Reqbin, and not sponsoring POSTMAN, but later solution can generate you Swift code (not beautiful), but understanding enough to spot issue between yours and theirs. — Larme, Oct 23 '19 at 08:31

Xavier L. · Accepted Answer · 2023-03-02T23:34:42.190

Here is the Problem:

Your member=John is what people generally refer to as a "URL query parameter". In general, URL requests have query parameters as a part of the URL string itself and not the request's httpbody.

Quick and Dirty Solution:

Simply removing

request.httpBody = "member=John".data(using: .utf8)!

and passing the whole "www.somelink.com/stuff/searchmembers?member=John" into your getAllMembers(urlString:) function should do the trick.

A Better Solution:

Let's say John's username is j o h n. Your function wouldn't make it past that first guard because spaces aren't valid URL string characters.

I like to use URLComponents because it saves me the trouble of having to handle spaces and such.

Here's how I'd write your function:

func getJohnMember(urlString: String) {

    //URLComponents to the rescue!
    var urlBuilder = URLComponents(string: urlString)
    urlBuilder?.queryItems = [
        URLQueryItem(name: "member", value: "j o h n")
    ]

    guard let url = urlBuilder?.url else { return }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("Admin", forHTTPHeaderField: "Login")
    request.setValue("Admin", forHTTPHeaderField: "Password")


    URLSession.shared.dataTask(with: request) { (data, response, error) in
        print(response)
        print(String(data: data, encoding: .utf8)) //Try this too!
    }.resume()
}

Just to be clear, I would pass "www.somelink.com/stuff/searchmembers" into this function's first parameter, urlString.

Now if I were to print(url) after the guard let, I'd get

www.somelink.com/stuff/searchmembers?member=j%20o%20h%20n

which works as one would expect.

score 3 · Answer 2 · answered Oct 23 '19 at 08:56

That member=John is a URL-query parameter, not part of the request body. So you need to add it to the URL itself.

func getAllMembers(urlString: String) {
    guard let url = URL(string: "\(urlString)?member=John") else { return }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("Admin", forHTTPHeaderField: "Login")
    request.setValue("Admin", forHTTPHeaderField: "Password")


    URLSession.shared.dataTask(with: request) { (data, response, error) in
        print(response)
        print(data)
    }.resume()
}

`URLQueryItem` is the correct way to add that member name, rather than appending to the url. The accepted answer covers this correctly. This will work, but... "It isn't wrong, but we just don't do it" - Gordon. — mylogon, Sep 02 '20 at 16:08

Passing headers to URL with Swift URLSession

2 Answers2