cannot invoke 'jsonObjectWithData' - ios

Question

I cannot figure out how to solve this issue.
This comes from a youtube tutorial to build a simple Weather App.
The tutorial was uploaded in March 2015 and therefor written in a previous version of Swift, there it worked, with the current Swift 2 it doesn't.
The error I get is: "cannot invoke 'jsonObjectWithData' with an argument list of type '(NSData, options: nil, error: NSError)'"
func getWeatherData(urlString:String) {
let url = NSURL(string: urlString)
let task = NSURLSession.sharedSession().dataTaskWithURL(url!){ (data, response, error) in
dispatch_async(dispatch_get_main_queue(), {
self.setLabels(data)
})
}
task.resume()
}
func setLabels(weatherData: NSData) {
var jsonError: NSError
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: jsonError)
if let name = json["name"] as? String {
self.ResultLabel.text = name
}
}

Answer 1

if you want to get this code ready for Swift 2, you have to run the JSONParser with try and catch possible errors.
private func httpGetRequest(request: NSURLRequest!, callback: (NSData?, String?) -> Void) {
let session = NSURLSession.sharedSession()
let task = session.dataTaskWithRequest(request){
(data, response, error) -> Void in
if error != nil {
callback(nil, error!.localizedDescription)
} else {
callback(data, nil)
}
}
task!.resume()
}
func setLabels(weatherData: NSData) {
do {
let json = try NSJSONSerialization.JSONObjectWithData(weatherData, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let name = json["name"] as? String {
self.resultLabel.text = name
}
} catch {
print(error)
self.resultLabel.text = "Lorem Ipsum"
}
}
func loadWeatherData() {
let weatherRequest = NSMutableURLRequest(URL: NSURL(string: "Your URL String goes here")!)
httpGetRequest(weatherRequest){
(data, error) -> Void in
if error != nil {
print("Error: \(error)")
} else {
self.setLabels(data!)
}
}
}
Hope that will help to solve your Problems.

Answer 2

Try this:
var jsonError: NSError?
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: &jsonError)

Answer 3

in swift 3.0 and Swift 4.2
try this ...
do {
let jsonData = try JSONSerialization.data(withJSONObject: your array or dictionary, options: JSONSerialization.WritingOptions()) as Data
let json = try JSONSerialization.jsonObject(with: jsonData as Data, options: JSONSerialization.ReadingOptions(rawValue: UInt(0)))
}
catch
{
}

Answer 4

You need to pass the error pointer into NSJSONSerialization.JSONObjectWithData(...) with &.
let json = NSJSONSerialization.JSONObjectWithData(weatherData, options: nil, error: &jsonError) // &jsonError points to the NSErrorPointer of the NSError object

Answer 5

In swift 3 you can try this:
func setLabels(weatherData: NSData) {
do {
var jsonError: NSError
let json = try JSONSerialization.jsonObject(with: weatherData as Data, options: []) as! NSDictionary
if let name = json["name"] as? String {
self.ResultLabel.text = name
}
} catch {
}
}

Answer 6

In Swift 3, you can fix the same error with the code below:
do{
let jsonData = try JSONSerialization.jsonObject(with: (data)!, options: JSONSerialization.ReadingOptions.mutableContainers) as! [String: AnyObject]
}catch{
print("Error while parsing JSON: Handle it")
}