How to work with Backendless REST API in swift 3 - ios

Question

I am trying to connect back endless rest api using IOS swift 3.
I am adding application id, secret key like below
request.addValue("0C896F8C-D3CE-BD08-FF1D-2B087CE77B00", forHTTPHeaderField: "application-id")
request.addValue("9D9A2BCD-F272-16E8-FF01-CD5AFD8CC300", forHTTPHeaderField: "secret-key")
And also I am getting
fatal error: unexpectedly found nil while unwrapping an Optional value
in this line of code
let strData = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("Body: \(strData)")
Can u anyone tell me whats going on…
let request = NSMutableURLRequest(url: NSURL(string:"/v1/users/login") as! URL)
let session = URLSession.shared
request.httpMethod = "POST"
let params = ["name":"mm", "password":"mm"] as Dictionary<String, String>
request.httpBody = try? JSONSerialization.data(withJSONObject: params, options: [])
request.addValue("0C896F8C-D3CE-BD08-FF1D-2B087CE77B00", forHTTPHeaderField: "application-id")
request.addValue("9D9A2BCD-F272-16E8-FF01-CD5AFD8CC300", forHTTPHeaderField: "secret-key")
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("REST", forHTTPHeaderField: "application-type")
request.addValue("application/json", forHTTPHeaderField: "Accept")
let task = session.dataTask(with: request as URLRequest, completionHandler: {data, response, error -> Void in
print("Response: \(response)")
let strData = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("Body: \(strData)")
let json = try! JSONSerialization.jsonObject(with: data!, options: .mutableLeaves)
print(json)
//JSONObjectWithData(data, options: .MutableLeaves, error: &err) as? NSDictionary
// Did the JSONObjectWithData constructor return an error? If so, log the error to the console
if(error != nil) {
// print(err!.localizedDescription)
let jsonStr = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("Error could not parse JSON: '\(jsonStr)'")
}
else {
// The JSONObjectWithData constructor didn't return an error. But, we should still
// check and make sure that json has a value using optional binding.
if let parseJSON = json as? NSDictionary { // Okay, the parsedJSON is here, let's get the value for 'uccess' out of it
let success = parseJSON["success"] as? Int
print("Succes: \(success)")
}
else
{
// Woa, okay the json object was nil, something went worng. Maybe the server isn't running?
let jsonStr = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print("Error could not parse JSON: \(jsonStr)")
}
}
})
task.resume()

Answer 1

You need to check the data is not nil first:
if let d = data {
let strData = NSString(data: d, encoding: String.Encoding.utf8.rawValue)
print("Body: \(strData)")
} else {
print(error)
}