Search code examples
jsonswiftnsjsonserialization

How to use Swift's JSONSerialization when JSON returns a single string

So this is likely a very basic question, but I was curious how you would handle parsing a JSON object that returns as a single string using JSONSerialization in Swift. So I'm playing around with a free Harry Potter API and noticed that one of the routes returns a single string (https://www.potterapi.com/v1/sortinghat) and the response it gives is simply a single string of one of the four houses in Harry Potter.

"Ravenclaw"

Below was my attempt.

do {
    let json = try JSONSerialization.jsonObject(with: data, options: []) as? String
    print("json: \(json)")
} catch {
    print("Error: \(error.localizedDescription)")
}

I thought simply typecasting as a String would suffice but I just get the following error: "Error: The data couldn’t be read because it isn’t in the correct format."

I know there are better ways to parse JSON such as using Codable but I am just trying to understand how this would work before moving on to tackling that.

Solution

  • JSONSerialization is the wrong tool for this. You want to use JSONDecoder, which is much more useful in Swift:

    let json = Data("""
"Ravenclaw"
""".utf8)

let result = try JSONDecoder().decode(String.self, from: json)

    Note that this requires iOS 13.1 or macOS 10.15.1. Otherwise you will need to use @vadian's answer.