Swift - How can I decode json string response into a String?

Question

Why doesn't this work?

let jsonResponse = " \"This is a response\" "

let str = try! JSONDecoder().decode(String.self, from: jsonResponse)

print(str)

error: cannot convert value of type 'String' to expected argument type 'Data'

In other languages, like javascript or java/kotlin, converting this response into a string is pretty easy.

JS

const s = JSON.parse(" \"This is a response\" ")

Kotlin

val s = Gson().fromJson(String::class.java, " \"This is a response\" ")

But in swift, it doesn't seem this straight forward. Is this response valid json? I assumed that the double quotes would make it a valid json object.

Thanks in advance.

You can check if your json is valid here.

koen
– koen

2020-06-18 18:57:05 +00:00
Commented Jun 18, 2020 at 18:57 — koen
– koen, Commented Jun 18, 2020 at 18:57

Frankenstein · Accepted Answer · 2020-06-18 18:48:18Z

3

You need to convert the String to Data first to decode it using JSONDecoder:

let jsonResponse = " \"This is a response\" "
let data         = Data(jsonResponse.utf8)
let str          = try! JSONDecoder().decode(String.self, from: data)
print(str)

answered Jun 18, 2020 at 18:48

Frankenstein

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2 Comments

SomeKoder Over a year ago

This code doesn't seem to work here, any ideas?

Frankenstein Over a year ago

This code runs perfectly on Xcode-playgrounds download it from here or if you have Xcode that's more than enough. The thrid-party playground you're using seems to be broken or outdated.

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