Swift: How can I parse a JSON response from a server if it's wrapped in an array? - arrays

Question

Swift n00b here.
I'm getting something like this as a response from a server:
[
{
"foo": [],
"bar":"asdf",
...
}
]
Now I understand how to parse regular JSON, but not when it has an array as the base element.
Here is code I used so far, which would work for regular JSON:
let task = session.dataTask(with: urlRequest) {
(data, response, error) in
// check for any errors
guard error == nil else {
print("error calling POST on \(String(describing: urlRequest.url?.absoluteURL))")
print(error!)
return
}
// make sure we got the data
guard let responseData = data else {
print("Error: did not receive data")
return
}
let responseString = String(data: responseData, encoding: String.Encoding.utf8) as String!
// parse the result as JSON, since that's what the API provides
do {
guard let todo = try JSONSerialization.jsonObject(with: responseData, options: [])
as? [String: Any] else {
print("error trying to convert data to JSON")
return
}
... // do whatever with the response
} catch {
print("an error occurred")
return
}
}
task.resume()
The error I'm getting from that is "error trying to convert data to JSON.
The easiest way to parse that response I can think of is making a substring from 1 to length - 1 and then parsing it, but that doesn't seem particularly safe.
Is there any way I can parse that response into a [Dictionary]?

Answer 1

Your JSON is regular JSON. An array at the top level is just as valid (and regular) as a dictionary.
Simply update your cast accordingly:
guard let todo = try JSONSerialization.jsonObject(with: responseData, options: [])
as? [[String: Any]] else {
That indicates that you have an array of dictionary. Now you can iterate the array and get each dictionary as needed.