JSONSerialization error in swift3 - json

Question

I am trying to post Audio file to an API, but I am getting an error
"*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (NSURL)'"
Here is my code:
let parameters = [fileUrl]
//create the url with NSURL
let url = NSURL(string: "httpblahblah")
//create the session object
let session = URLSession.shared
//now create the NSMutableRequest object using the url object
let request = NSMutableURLRequest(url: url! as URL)
request.httpMethod = "POST" //set http method as POST
do {
request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted) // pass dictionary to nsdata object and set it as request body
} catch let error {
print(error.localizedDescription)
}
//HTTP Headers
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
//create dataTask using the session object to send data to the server
let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in
guard error == nil else {
return
}
guard let data = data else {
return
}
do {
//create json object from data
if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: AnyObject] {
print(json)
// handle json...
}
} catch let error {
print(error.localizedDescription)
}
})
task.resume()

Answer 1

When you create request.httpBody, you're passing in the parameters array you declared above:
let parameters = [fileUrl]
It's not clear from your code, but if fileUrl is an NSURL instead of a String, that would cause the error you see. The documentation for JSONSerialization says:
All objects are instances of NSString, NSNumber, NSArray,
NSDictionary, or NSNull.
so trying to sneak in an NSURL will definitely not work.
Assuming that your intention is to serialize fileUrl as a String, you can do that by changing the declaration to:
let parameters = [fileUrl.absoluteString!]
If you want to send the actual file data, you're not going to be able to serialize it in a JSON object. Check out this question and its answer for a good example of sending data from a file to a server. Depending on the API you're working with you may still need the JSON object for other data, and its structure will be determined by the API.

Answer 2

From what I understand you are trying to upload a audio file, with a URL reference instead of Data.
Get correct Data format from URL with this:
let data = FileManager.default.contents(atPath: fileUrl.path)
request.httpBody = data