Completion handler with POST request - ios

Question

I have simple login method which returns bool, depends on success of user login. I have problem with order of the responses and execution of the code. I've read about completion handlers, which I think are a solution to my problem but I'm not sure. Here is my method:
//perform user login in, setting nsuserdefaults and returning the bool result
func login(username: String, password:String) -> (Bool) {
var success:Bool = false
//sending inputs to server and receiving info from server
let postRequest = postDataToURL()
postRequest.link = "http://pnc.hr/rfid/login.php"
postRequest.postVariables = "username=" + username + "&password=" + pass
word
postRequest.forData("POST") { jsonString in
// getting the result from the asinhronys task
let result = convertStringToDictionary(jsonString as String)
if let loggedIn = result?["loggedIn"] as? Bool where loggedIn == true {
let userType = result?["userType"] as? String
let token = result?["token"] as? String
//if user is logged - setting parameters in Key Chains and redirecting them to the menu view
let defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(loggedIn, forKey: "loggedIn")
defaults.setObject(username, forKey: "username")
defaults.setObject(userType, forKey: "userType")
defaults.setObject(token, forKey: "token")
success = true
}
else {
success = false
}
print ("class - " + String(jsonString))
print ("classIN - " + String(success))
}
print ("classOUT - " + String(success))
return success
}
I would like to make return of success variable inside if statement which checks variable loggedIn is equal to true. But in that case I get error.
Then I have made this method. The problem is that method returns the variable success quicker than the POST request has been done. So it will be false in every case. I have printed variables to see the order of the code execution and method first prints the "classOUT", returns the variable, and then sets up variable value and print "classIN".
How can I wait until the code which logs user gets executed so I can get the right value of the variable success?

Answer 1

Perform user login in, setting nsuserdefaults and returning the bool result
completionBlock: is that block which will get executed when you call it like any block but you get to choose when and what all to pass through that block.
func login(username: String, password:String,completionBlock : ((success : Bool)->Void)){
//sending inputs to server and receiving info from server
let postRequest = postDataToURL()
postRequest.link = "http://pnc.hr/rfid/login.php"
postRequest.postVariables = "username=" + username + "&password=" + password
postRequest.forData("POST") { jsonString in
// getting the result from the asinhronys task
let result = convertStringToDictionary(jsonString as String)
if let loggedIn = result?["loggedIn"] as? Bool where loggedIn == true {
let userType = result?["userType"] as? String
let token = result?["token"] as? String
//if user is logged - setting parameters in Key Chains and redirecting them to the menu view
let defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(loggedIn, forKey: "loggedIn")
defaults.setObject(username, forKey: "username")
defaults.setObject(userType, forKey: "userType")
defaults.setObject(token, forKey: "token")
completionBlock(success:true)
}
else {
completionBlock(success:false)
}
}
}
when you call it would look something like this:-
login(username: String, password:String,completionBlock : { (success) in
print(success)
})

Answer 2

you could do something like this
func login(username: String, password: String, completion: (Bool) -> ()) {
... YOUR USUAL NETWORKING CODE ...
completion(success)
}
and then call it
login(username: anonymous, password: ******) { authStatus in
if authStatus == true {
print("user in")
} else {
print("try one more time")
}
}