var accountAlertView: AccountAlertView = AccountAlertView()

...

override func viewDidLoad() {
    
    accountAlertView.loginWithUsername = {
        (username: String!, password: String!, completed: () -> (), failed: (message: String!) -> ()) in
        
        if self.isRequestSuccessful {
            completed()
        } else {
            failed(message: "Failed Request.")
        }
    }
    
    accountAlertView.signUpWithUsername = {
        (username: String!, password: String!, completed: () -> (), failed: (message: String!) -> ()) in
        
        if self.isRequestSuccessful {
            completed()
        } else {
            failed(message: "Failed Request.")
        }
    }
    
    accountAlertView.showAccountAlert()
}