objective c - iOS 8 Swift 1.2 and Parse - Attempt to present UIAlertController on ViewController whose view is not in the window hierarchy -

there many questions on stack concerning issue, none of them seem solve issue i'm having.

i using parseui login , signup portion of application. like have happen uialertcontroller presented when user (for example) not enter in text in username , password fields.

here code masterviewcontroller:

class masterviewcontroller: uiviewcontroller, pfloginviewcontrollerdelegate, pfsignupviewcontrollerdelegate {      override func viewdidload() {         super.viewdidload()         // additional setup after loading view.     }      override func viewdidappear(animated: bool) {         super.viewdidappear(animated)          if (pfuser.currentuser() == nil) {             var loginviewcontroller = loginviewcontroller()             loginviewcontroller.delegate = self              var signupviewcontroller = signupviewcontroller()             signupviewcontroller.delegate = self              loginviewcontroller.signupcontroller = signupviewcontroller              self.presentviewcontroller(loginviewcontroller, animated: true, completion: nil)          }     }      func loginviewcontroller(logincontroller: pfloginviewcontroller,         shouldbeginloginwithusername username: string, password: string) -> bool {              if (!username.isempty || !password.isempty) {                 return true             } else {                 let alertcontroller = uialertcontroller(title: "failed login.",                     message: "login failure.  please try again.", preferredstyle: .alert)                  let defaultaction = uialertaction(title: "ok", style: .default, handler: nil)                 alertcontroller.addaction(defaultaction)                  self.presentviewcontroller(alertcontroller, animated: true, completion: nil)                   return false             }     }        func loginviewcontroller(logincontroller: pfloginviewcontroller,         didfailtologinwitherror error: nserror?) {              println("failed log in.")      }       func signupviewcontroller(signupcontroller: pfsignupviewcontroller,         shouldbeginsignup info: [nsobject : anyobject]) -> bool {              if let password = info["password"] as? string {                 return count(password.utf16) >= 8             } else {                 return false             }     }      func signupviewcontroller(signupcontroller: pfsignupviewcontroller,         didfailtosignupwitherror error: nserror?) {              println("failed sign up.")      }      func loginviewcontroller(logincontroller: pfloginviewcontroller,         didloginuser user: pfuser) {             let installation = pfinstallation.currentinstallation()             installation["user"] = pfuser.currentuser()             installation.saveinbackground()             self.dismissviewcontrolleranimated(true, completion: nil)     }       override func didreceivememorywarning() {         super.didreceivememorywarning()         // dispose of resources can recreated.     }       func signupviewcontrollerdidcancelsignup(signupcontroller:         pfsignupviewcontroller) {              println("user dismissed signup.")      } } 

after reading user's answer seemed answer, added following class workspace:

import foundation  class alerthelper: nsobject {     func showalert(fromcontroller controller: masterviewcontroller) {         var alert = uialertcontroller(title: "abc", message: "def", preferredstyle: .alert)         controller.presentviewcontroller(alert, animated: true, completion: nil)     } } 

and modified method accordingly:

func loginviewcontroller(logincontroller: pfloginviewcontroller, shouldbeginloginwithusername username: string, password: string) -> bool {

    if (!username.isempty || !password.isempty) {         return true     } else {         let alertcontroller = uialertcontroller(title: "failed login.",             message: "login failure.  please try again.", preferredstyle: .alert)          let defaultaction = uialertaction(title: "ok", style: .default, handler: nil)         alertcontroller.addaction(defaultaction)          var alert = alerthelper()         alert.showalert(fromcontroller: self)          return false     } 

}

at point i'm not quite sure else do. 1 thought had programmatically add uilabel loginviewcontroller , signupviewcontroller , change content based on errors (or lack thereof) user login , signup, have alerts.

edit: code in loginviewcontroller. subclassed in order customize appearance. code signupviewcontroller identical.

import uikit import parse import parseui

class loginviewcontroller: pfloginviewcontroller {    override func viewdidload() {     super.viewdidload()      view.backgroundcolor = ckpurple      let label = uilabel()     label.textcolor = uicolor.whitecolor()     label.text = "welcome."     label.sizetofit()     loginview?.logo = label      // additional setup after loading view.   } 

the problem present login view controller master view controller, removes master view controller view hierarchy. attempt present alert view controller master view controller, need present view controller in view hierarchy. try presenting alert from login view controller instead.

logincontroller.presentviewcontroller(alertcontroller, animated: true, completion: nil)