How to navigate to another viewcontroller after getting response from the server - ios

Question

I am trying to login through the swift.
I am getting the proper data in the form of json and able to extract the data, but when I try to print the success message in the terminal then I need to press the login button twice.
#IBAction func loginButton(sender: UIButton) {
//test.text = usernameText.text
let user = usernameText.text!
let pass = passwordText.text!
let a = "http://www.example.com/app/login.php?username="
let b = "&password="
let c = a + user + b + pass
let url = NSURL(string: "\(c)")!
let task = NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) -> Void in
if let urlContent = data {
do {
let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(urlContent, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
if let custdetails : [NSDictionary] = jsonResult["data"] as? [NSDictionary] {
for person: NSDictionary in custdetails {
//for (name,value) in person {
// print("\(name) , \(value)")
//print(person.valueForKey("CustId")!)
//}
let userid:String = person.valueForKey("CustId") as! String
print(userid)
//NSUserDefaults.standardUserDefaults().setBool(true, forKey: "IsUserLoggedIn")
NSUserDefaults().setString(userid, forKey: "userName")
NSUserDefaults.standardUserDefaults().synchronize()
self.dismissViewControllerAnimated(true, completion: nil)
self.message = jsonResult["message"] as! String
}
}
} catch {
print("JSON serialization failed")
}
}
}
task.resume()
print(message)
//navingation code
}
I have printed the userid when I get from the json
SO when I click on the login button I can see the id in the console, but cant see the message which I have printed on the second last line
When I again click on the login button then message is printed and the id is also printed again which means my code runs second time.
Thanks for helping me in advance
Any help will be appreciated.

Answer 1

You need to dispatch_async your JSON results. You can read up more here. You can also use AlamoFire or SwiftyJSON to help you with this. These are very good JSON tools. You can google them.
First, declare your userid variable outside of the JSON response. Preferably at the first line of your method. Then update your codes as below.
for person: NSDictionary in custdetails {
userid = person.valueForKey("CustId") as! String
} dispatch_async(dispatch_get_main_queue(),{
print(userid)
if(userid != ""){
self.dismissViewControllerAnimated(true, completion: nil)
self.message = jsonResult["message"] as! String
}
})