Importing Firebase causes JSON fetching ambiguous - json

Question

I have been fetching JSON in my View Controller, and I needed a function to add data in that same VC to firebase, so imported Firebase ( Pods firebase core, auth and firestore ) and now it gives me an error on JSON fetching that it's Ambiguous use of 'subscript'
func getDetails(link: URL!) {
var plot : String = " "
let task = URLSession.shared.dataTask(with: link!) { (data, response, error) in
if error != nil
{
print("error")
}
else
{
if let content = data
{
do
{
//JSON results
let myJson = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableLeaves) as AnyObject
//myJson ~~~ ["Plot"] Ambiguous use of 'subscript'
plot = myJson["Plot"] as! String
}
catch
{
print("error in JSONSerialization")
}
}
}
}
task.resume()
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5, execute: {
self.plot.text = plot
})
}
I would love to maintain ability to pick the "Plot" value of JSON and have the firebase running

Answer 1

Your problem is casting result from JSONSerialization to AnyObject. If you want to be able to use subscript, you should, in your case, downcast result to dictionary type, for example [String:Any]
if let myJson = try JSONSerialization.jsonObject(with: content, options: .mutableLeaves) as? [String:Any] {
// plot = myJson["Plot"] as? String ?? "Default value"
}
Anyway, rather learn something about Codable and use it instead of JSONSerialization. Just create class/struct conforming to Decodable protocol and then use JSONDecoder to decode Data object.

Answer 2

Here's how I would rewrite this method, given a ModelObject struct or class that represents your server response.
func getDetails(link: URL!) {
var plot = " "
let group = DispatchGroup()
group.enter()
let task = URLSession.shared.dataTask(with: link!) { (data, response, error) in
defer { group.leave() }
guard error == nil else {
print(error)
return
}
if let content = data {
do {
let modelObject = try JSONDecoder().decode(ModelObject.self, from: data)
plot = modelObject.plotString
}
catch {
print(error)
}
}
}
task.resume()
group.notify(queue: DispatchQueue.main) {
self.plot.text = plot
}
}