Following is the storyboard of my app:
The app establishes a connection with the server on screen1 and all the communication with the server is performed in the code of this screen only. We make a request on screen4 and send it to server through the code of screen1 and app receives the response from the sever. If app gets successful response then app should show screen5, where I get error.
I wrote different lines of code but failed. Following are line of code which I am using now:
import UIKit
class logoViewController: UIViewController {
#IBOutlet weak var act: UIActivityIndicatorView!
override func viewDidLoad() {
super.viewDidLoad()
self.act.startAnimating()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// syncreq function is called from the connectionViewController.
// connectionViewController is the common class for connecting to the remote server
func syncreq (JSONdata: AnyObject) { // Proceesing for PRMS response
// Getting the value from the JSON
var Successful = self.getIntFromJSON(JSONdata as NSDictionary, key: "Successful")
println("Value of Successful : \(Successful)")
if (Successful == 0){
//Method1 not worked
// let adduser = regVC()
// self.presentViewController(adducer, animated: true, completion: nil)
//Method2 not worked
//let adducer = self.storyboard?.instantiateViewControllerWithIdentifier("registrationID") as regVC
//self.navigationController?.pushViewController(adducer, animated: true)
//Method3 not worked
//let secondViewController = self.storyboard?.instantiateViewControllerWithIdentifier("registrationID") as regVC
//self.navigationController?.pushViewController(secondViewController, animated: true)
//performSegueWithIdentifier("registrationID", sender: self)
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
var setViewController = mainStoryboard.instantiateViewControllerWithIdentifier("registrationID") as RegisterViewController
self.presentViewController(setViewController, animated: false, completion: nil)
}
else if (Successful == 1){
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
var setViewController = mainStoryboard.instantiateViewControllerWithIdentifier("mnuID") as menuViewController
self.presentViewController(setViewController, animated: false, completion: nil)
}
}
func getIntFromJSON(data: NSDictionary, key: String) -> Int {
let info : AnyObject? = data[key]
// println("Value of data[key] : \(key)")
if let info = data[key] as? Int {
println("Value of value for \(key) : \(info)")
return info
}
else {
return 0
}
}
}
I got the following error:
Warning: Attempt to present <project.screen5: 0x7a094790> on <project.ViewController: 0x79639d90> whose view is not in the window hierarchy!
screenshot of error:
Your problem is that view of the ViewController 1 is not in the window hierarchy, thus ViewController 1 cannot present modal VC.
Cleanest fix would be to change your app architecture design - having one view controller perform all the network requests may cause more complications than just this one.
However, for 'just make it work' solution you can present modal VC from navigation controller, i.e.
self.navigationController?.presentViewController(setViewController, animated: false, completion: nil)
Related
Goal: In a separate storyboard that is loaded via a storyboard reference in the main.storyboard, in a pageViewController acting as the initial view controller, I want to initialize an array object of viewControllers via the function .instantiateViewController(identifier:).
Issue: The last viewController I'm trying to instantiate as a constant is not loading. The error - *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load the scene view controller for identifier 'FinalVC''"
All other viewControllers in this storyboard load fine. This last view controller has a correct custom class linked and a unique storyboard identifier.
Debugging: I've created a breakpoint where this view controller is instantiated and noticed in the debugging console all other view controller objects load as "BillyCues.repeatViewController + unique identification number" while this last vc loads as "UIViewController + 0x000000000000000". It's almost as if this vc is not a part of the app bundle or referenced correctly but it's there when I search in the directory.
Debugging console screen
Things I've tried that did not work:
Check to see if another vc has the same identifier
Clean the build folder
Check "Use Storyboard ID" in the identity inspector
let finalVC = storyBoard.instantiateViewController(identifier: "FinalVC") as! FinalViewController
Restart Xcode
Create a brand new view controller with a different storyboard identifier using the same custom class
Removed all connections from buttons and labels in the last vc
Made sure all storyboard references in main.storyboard has the correct storyboard linked
Conclusion: All my googling has led to other developers encountering the error about NIBs or tableviews not necessarily a view controller. If my vc has a correct custom class and unique identifier the error should not occur. If anyone can offer guidance I'd appreciate it; I'm dumbfounded.
I hope I've asked for help in an appropriate structure but please let me know if more code or screenshots are needed.
PageViewController Code
import UIKit
class LauncherViewController: UIPageViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.setViewControllers([viewControllerList[0]], direction: .forward, animated: false, completion: nil)
// Do any additional setup after loading the view.
}
private var viewControllerList: [UIViewController] = {
let storyBoard = UIStoryboard.cueCreation
let firstVC = storyBoard.instantiateViewController(identifier: "CueNameVC")
let secondVC = storyBoard.instantiateViewController(identifier: "DueDateVC")
let thirdVC = storyBoard.instantiateViewController(identifier: "IconVC")
let fourthVC = storyBoard.instantiateViewController(identifier: "IconColorVC")
let fifthVC = storyBoard.instantiateViewController(identifier: "RepeatVC")
let finalVC = storyBoard.instantiateViewController(identifier: "FinalVC") as! FinalViewController
return [firstVC, secondVC, thirdVC, fourthVC, fifthVC, finalVC]
}()
var selectedReminderBill: CueObject?
public var currentIndex = 0
static var cueName: String = ""
static var cueDate: Date = Date()
static var cueIcon: Data = Data()
static var iconColor:String = "14CC7F"
static var repeatMonthly: Bool = false
// Navigation button functions below to move to the next or previous page
func pushNext() {
if currentIndex + 1 < viewControllerList.count {
self.setViewControllers([self.viewControllerList[self.currentIndex + 1]], direction: .forward, animated: true, completion: nil)
currentIndex += 1
}
}
func pullBack() {
print(currentIndex)
if currentIndex - 1 < viewControllerList.count {
self.setViewControllers([self.viewControllerList[self.currentIndex-1]], direction: .reverse, animated: true, completion: nil)
currentIndex -= 1
}
}
}
FinalViewController Code
import UIKit
import UserNotifications
import RealmSwift
class FinalViewController: UIViewController {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
cueName.text = LauncherViewController.cueName
dueDate.text = CueLogic.convertPaymentDateToString(for: LauncherViewController.cueDate)
iconBackgroundView.backgroundColor = colorLogic.colorWithHexString(hexString: LauncherViewController.iconColor)
cueIcon.image = UIImage(data: LauncherViewController.cueIcon)
repeatsMonthly.text = repeatMonthlyToString
}
override func viewDidLoad() {
super.viewDidLoad()
cueName.layer.cornerRadius = 15
cueName.clipsToBounds = true
iconBackgroundView.layer.cornerRadius = 20
iconBackgroundView.clipsToBounds = true
dueDate.layer.cornerRadius = 15
dueDate.clipsToBounds = true
repeatsMonthly.layer.cornerRadius = 15
repeatsMonthly.clipsToBounds = true
backButton.layer.cornerRadius = 15
backButton.clipsToBounds = true
saveButton.layer.cornerRadius = 15
saveButton.clipsToBounds = true
// Do any additional setup after loading the view.
}
let colorLogic = ColorLogic()
let realm = try! Realm()
weak var delegate: HomeScreenDelegate?
var launcher = LauncherViewController()
var repeatMonthlyToString: String {
get {
if LauncherViewController.repeatMonthly == true {
return "Repeats Monthly: Yes"
} else {
return "Repeats Monthly: No"
}
}
}
#IBOutlet var cueName: UILabel!
#IBOutlet var dueDate: UILabel!
#IBOutlet var saveButton: UIButton!
#IBOutlet var backButton: UIButton!
#IBOutlet var iconBackgroundView: UIView!
#IBOutlet var cueIcon: UIImageView!
#IBOutlet var repeatsMonthly: UILabel!
#IBAction func dismissButtonTapped(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
#IBAction func backButtonTapped(_ sender: Any) {
if let pageController = parent as? LauncherViewController {
pageController.pullBack()
}
}
#IBAction func saveButtonTapped(_ sender: Any) {
// Request authorization from the user to allow notifications
UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound], completionHandler: {success, error in
if success {
// schedule test
} else if let error = error {
print("error occured \(error)")
}
})
let newCue = CueObject()
let launcherVC = LauncherViewController.self
newCue.name = launcherVC.cueName
newCue.paymentDate = launcherVC.cueDate
newCue.icon = launcherVC.cueIcon
newCue.iconColor = launcherVC.iconColor
newCue.repeatsMonthly = launcherVC.repeatMonthly
NotificationLogic.scheduleLocalAlertForBill(named: newCue.name, due: newCue.paymentDate, repeatsMonthly: newCue.repeatsMonthly)
saveToDB(for: newCue)
delegate?.loadCuesFromRealm()
self.dismiss(animated: true, completion: nil)
}
func saveToDB(for cue: CueObject) {
do {
try realm.write({
realm.add(cue)
})
} catch {
print("Error - \(error)")
}
}
}
protocol HomeScreenDelegate: AnyObject {
func loadCuesFromRealm()
}
Extension I wrote in another viewController
extension UIStoryboard {
static let onboarding = UIStoryboard(name: "Onboarding", bundle: nil)
static let main = UIStoryboard(name: "Main", bundle: nil)
static let cueCreation = UIStoryboard(name:"CueCreation", bundle: nil)
}
Identity Inspector
Main Storyboard References
I'd do a few things as part of cleanup to start debugging the actual issue. In the storyboard extension, I'd rather use a static function to reference the view controller.
extension UIStoryboard {
class func createFinalVC() -> FinalViewController? {
return UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "FinalVC") as? FinalViewController)
}
}
And for implementing it, I'd use in the view controller presenting FinalViewController:
private func createCreateFinalVC() -> FinalViewController? {
return UIStoryboard.createFinalVC()
}
And finally pushing it into the view,
if let finalVC = createCreateFinalVC() {
yourNavController?.pushViewController(finalVC, animated: true)
}
Solution
I began a process of elimination and started to comment out all of the code in my FinalVC class. I learned that this line of code var launcher = LauncherViewController() was triggering the crash.
Given my limited beginner knowledge I don't know why this would cause a crash; I can only assume that Xcode was trying to initialize two LauncherViewControllers with identical identifier numbers or something along those lines.
nil Delegate between two ViewController with two different Bundle using swift 4 (commented in second code)
here is my code :
First ViewController :
class FirstVC : UIViewController, MerchantResultObserver{
var secVC = SecondVC()
override func viewDidLoad() {
secVC.delegate = self
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
let controller = storyboard.instantiateInitialViewController()
self.present(controller!, animated: true, completion: nil)
secVC.initSecondVC(data)
}
func Error(data: String) {
print("-------------Error Returned------------- \(data)")
}
func Response(data: String) {
print("-------------Response Returned------------- \(data)")
}
}
Second ViewController :
public class SecondVC: UIViewController {
public weak var delegate: MerchantResultObserver!
public func initSecondVC(_ data : String){
print(data)
}
#IBAction func sendRequest(_ sender: UIButton) {
delegate?.Response(data: “dataReturnedSuccessfully”) // delegate is nil //
dismiss(animated: true, completion: nil) // returned to FirstVC without returning “dataReturnedSuccessfully” //
}
}
public protocol MerchantResultObserver: class{
func Response(data : String)
func Error(data : String)
}
Any help would be appreciated
var secVC = SecondVC()
and
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
let controller = storyboard.instantiateInitialViewController() as? SecondVC
These both are different instances.
You can assign a delegate to the controller, like
controller.delegate = self
It will call the implemented delegate methods in First View Controller.
Full Code.
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
if let controller = storyboard.instantiateInitialViewController() as? SecondVC {
//Assign Delegate
controller.delegate = self
//It's not init, but an assignment only, as per your code.
controller.initSecondVC(data)
self.present(controller, animated: true, completion: nil)
}
One more thing, Don't present View in ViewDidLoad. You can put a code in some button or in a delay method.
I am pretty new to programming, thats why I can't really figure out how to solve this issue.
I have implemented a rootviewcotnroller in the app delegate so that if the user is logged in he is pushed directly to the app content instead of the login view controller.
However it doesn't really work. As is already said I added the following code to the app delegate:
window = UIWindow(frame: UIScreen.main.bounds)
window?.makeKeyAndVisible()
window?.rootViewController = MainViewController()
The MainViewcontroller is set up like this:
class MainViewController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
if isLoggedIn() {
let homeController = UserViewController()
viewControllers = [homeController]
}else {
perform(#selector(showLoginController), with: nil, afterDelay: 0.01)
}
}
fileprivate func isLoggedIn() -> Bool {
return UserDefaults.standard.isLoggedIn()
}
func showLoginController() {
let loginController = LoginViewController()
present(loginController, animated: true, completion: {
})
}
}
To the Userviewcontroller I have added the following lines:
func handleSignout() {
UserDefaults.standard.setisLoggedIn(value: false)
print("is logged out")
}
#IBAction func SignOut(_ sender: Any) {
handleSignout()
if FIRAuth.auth()!.currentUser != nil {
do {
try? FIRAuth.auth()?.signOut()
if FIRAuth.auth()?.currentUser == nil {
let loginViewViewcontroller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Login") as! LoginViewController
self.present(loginViewViewcontroller, animated: true, completion: nil)
}
}
}
}
Then I have created an extension with the UserDefaults to save the boolean Value whether the user is logged in or logged out:
extension UserDefaults {
enum UserDefaultKeys: String {
case isLoggedIn
}
func setisLoggedIn(value: Bool) {
set(false, forKey: UserDefaultKeys.isLoggedIn.rawValue)
synchronize()
}
func isLoggedIn() -> Bool {
return bool(forKey: UserDefaultKeys.isLoggedIn.rawValue)
}
}
In the LoginviewController, which just shows a black screen if shown at first sight, I have added :
func finishLoggingIn() {
let rootViewController = UIApplication.shared.keyWindow?.rootViewController
guard let MainNavigationController = rootViewController as? MainViewController else {return}
MainNavigationController.viewControllers = [UserViewController()]
print("is logged in")
UserDefaults.standard.setisLoggedIn(value: true)
dismiss(animated: true, completion: nil)
}
This function is called when user pushes the login button.
The app recognizes if the user is logged or not, but it doesn't matter if the user is logged in or not, that first view controller which is presented shows a black screen, which is most likely the loginviewcontroller but if the user is logged in the userviewcontroller shows a black screen as well if is the first view controller to be presented. ...
Has anybody an idea why that is?
I have figured out how to solve it. It is way easier then I expected it to be. Maybe the solution I've found is not the best way of doing it, but as long as it works I am happy!
I deleted all function with the UserDefaults.
To my MainViewController I have just added a the following code, which is suggested by Firebase itself:
import UIKit
import FirebaseAuth
// DIeser Viewcontroller wird immer als erstes aufgerufen und entscheidet, ob der loginviewcontroller gestartet wird oder der UserViewController gestartet wird.
class MainViewController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
FIRAuth.auth()?.addStateDidChangeListener() { (auth, user) in
if user != nil {
let LoginVc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "usersVC")
self.present(LoginVc, animated: true, completion: nil)
}else {
let UserVc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "LoginVc")
self.present(UserVc, animated: true, completion: nil)
}
}
}
}
The MainViewController is still set as the rootviewcontroller in the AppDelegate.
I hope I helps someone else in the future!
My table view cell displays an entity with two different button elements. I want to be able to launch a view controller that displays a selection of food items if I click on the first button and a different view controller that displays a selection of beverages when I click on the second button.
I am able to correctly pass the data to the new view controllers, but can't seem to dismiss the current view and load the new one. My code is like this:
In the table view cell
#IBAction func foodBtnPressed(_ sender: Any) {
print("foodBtn pressed")
print("customer is \(customer?.name)")
vc.loadChooserScreen(toChoose: "Food", forCustomer: customer!)
}
#IBAction func beverageBtnPressed(_ sender: UIButton) {
print("beverageBtn pressed")
print("customer is \(customer?.name)")
vc.loadChooserScreen(toChoose: "Beverage", forCustomer: customer!)
}
In the table view controller
func loadChooserScreen(toChoose: String, forCustomer: Customer) {
print("Choose \(toChoose)")
print("For \(forCustomer.name)")
if toChoose == "Food" {
let foodVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "foodMenu") as? FoodVC
foodVC?.loadCustomerToEdit(customer: forCustomer)
dismissVC(sender: Any.self)
}
else if toChoose == "Beverage" {
let beverageVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "beverageMenu") as? BeverageVC
beverageVC?.loadCustomerToEdit(customer: forCustomer)
dismissVC(sender: Any.self)
}
else {
// do nothing
}
}
func dismissVC(sender: Any) {
print("Reached dismissVC function in selectionMenu")
dismiss(animated: true, completion: {
self.delegate!.dismissViewController()
})
}
In this view controller I also have the following protocol
protocol OrderVCProtocol {
func dismissViewController()
}
and have defined
var delegate: OrderVCProtocol!
In my root view controller
func dismissViewController() {
print("Reached dismissViewController function in rootView")
if let foodVC = self.storyboard?.instantiateViewController(withIdentifier: "foodMenu") {
self.present(foodVC, animated: true, completion: nil)
}
if let beverageVC = self.storyboard?.instantiateViewController(withIdentifier: "beverageMenu") {
self.present(beverageVC, animated: true, completion: nil)
}
}
And the delegate is set when the table view controller is called here
#IBAction func loadOrderView(_ sender: Any) {
let orderVC = self.storyboard?.instantiateViewController(withIdentifier: "orderView") as! OrderVC
orderVC.delegate = self
self.present(orderVC, animated: true, completion: nil)
}
Within my target view controllers I have the following function
func loadCustomerToEdit(customer: Customer) {
self.customerToEdit = customer
print("IN FoodVC THE CUSTOMER TO EDIT IS \(self.customerToEdit.name)")
}
and a corresponding one in the BeverageVC.
When I run the app, no errors are thrown and I get the following sample output in the console from my print statements:
foodBtn pressed
customer is Optional("John")
Choose Food
For Optional("John")
IN FoodVC THE CUSTOMER TO EDIT IS Optional("John")
Reached dismissVC function in selectionMenu
and a corresponding response if the beverage button is clicked.
Then nothing happens. So I know the data is correctly being passed to the new view controllers but I don't know how to dismiss the current screen and display the new one with the choices.
I hope my question is clear enough? I'm not sure what's wrong, but the console output clearly shows that the code runs fine until it tries to dismiss the current view.
EDITED TO ADD:
If I modify my dismissVC function in my tableview controller like this:
func dismissVC(sender: Any) {
print("Reached dismissVC function in selectionMenu")
delegate.dismissViewController()
}
the console view now throws
fatal error: unexpectedly found nil while unwrapping an Optional value
And if I modify it again to the following, It goes back to throwing no errors and getting stuck at the same place (i.e. printing the line "Stuck where delegate dismisses view"), showing that the delegate is still nil... but why is it nil when I'd set it in the root view and loaded it in this view?
func dismissVC(sender: Any) {
print("Reached dismissVC function in selectionMenu")
if delegate != nil {
delegate?.dismissViewController()
} else {
print("Stuck where delegate dismisses view")
}
I have solved my problem by implementing notifications via notification centre and delegates. Firstly, in my AppDelegate file I added this line at the bottom
let notifyCnt = NotificationCenter.default
Next, I modified my tableview cell functions to this
#IBAction func foodBtnPressed(_ sender: Any) {
notifyCnt.post(name: NSNotification.Name(rawValue: "toChoose"), object: nil, userInfo: ["toChoose": "Food", "forCustomer": customer])
}
#IBAction func beverageBtnPressed(_ sender: UIButton) {
notifyCnt.post(name: NSNotification.Name(rawValue: "toChoose"), object: nil, userInfo: ["toChoose": "Beverage", "forCustomer": customer])
}
Then, in the tableview controller I modified it to this:
protocol ChooserViewDelegate: class {
func loadChooserView(choice: String, forCustomer: Customer)
}
and defined
weak var delegate: ChooserViewDelegate?
and added this within my ViewDidLoad section
notifyCnt.addObserver(forName: Notification.Name(rawValue: "toChoose"), object: nil, queue: nil, using: loadChooserScreen)
and finally modified my chooser function like so:
func loadChooserScreen(notification: Notification) {
guard let userInfo = notification.userInfo,
let toChoose = userInfo["toChoose"] as? String,
let planToEdit = userInfo["customer"] as? Customer else {
print("No userInfo found in notification")
return
}
delegate?.loadChooserView(choice: toChoose, forCustomer: customer)
}
Then in my root view controller I have the following to replace what I had earlier:
/*Conform to ChooserViewDelegate Protocol */
func loadChooserView(choice: String, forCustomer: Customer) {
self.customer = forCustomer
dismiss(animated: false, completion: {
if choice == "Food" {
self.performSegue(withIdentifier: "food", sender: self.customer)
}
if choice == "Beverage" {
self.performSegue(withIdentifier: "beverage", sender: self.customer)
}
})
}
and I send over the data via prepareForSegue:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "food" {
if let foodVC = segue.destination as? FoodVC {
storyboard?.instantiateViewController(withIdentifier: "food")
foodVC.customerToEdit = self.customerToEdit
foodVC.delegate = self
}
}
if segue.identifier == "beverage" {
if let beverageVC = segue.destination as? BeverageVC {
storyboard?.instantiateViewController(withIdentifier: "beverage")
beverageVC.customerToEdit = self.customerToEdit
beverageVC.delegate = self
}
}
}
So now everything loads and views correctly :)
I recently started to learn swift and it has been pretty good so far. Currently I'm having an issue trying to pass data between view controllers. I managed to figure out how to programmatically navigate between two view controllers using a navigation controller. Only problem is now I'm having a hard time trying to figure out how to pass three string entered by the user (for json api) to the next view.
Here's my current attempt. Any help is much appreciated!
ViewController:
/* Get the status code of the connection attempt */
func connection(connection:NSURLConnection, didReceiveResponse response: NSURLResponse){
let status = (response as! NSHTTPURLResponse).statusCode
//println("status code is \(status)")
if(status == 200){
var next = self.storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as! SecondViewController
self.presentViewController(next, animated: false, completion: nil)
}
else{
RKDropdownAlert.title("Error", message:"Please enter valid credentials.", backgroundColor:UIColor.redColor(), textColor:UIColor.whiteColor(), time:3)
drawErrorBorder(usernameField);
usernameField.text = "";
drawErrorBorder(passwordField);
passwordField.text = "";
}
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject!) {
let navigationController = segue.destinationViewController as! UINavigationController
let newProjectVC = navigationController.topViewController as! SecondViewController
newProjectVC.ip = ipAddressField.text
newProjectVC.username = usernameField.text
newProjectVC.password = passwordField.text
}
SecondViewController:
import UIKit
class SecondViewController: UIViewController {
var ip:NSString!
var username:NSString!
var password:NSString!
override func viewDidLoad() {
super.viewDidLoad()
println("\(ip):\(username):\(password)")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
The method prepareForSegue is called when your app's storyboard performs a segue (a connection that you create in storyboards with Interface Builder). In the code above though you are presenting the controller yourself with presentViewController. In this case, prepareForSegue is not fired. You can do your setup right before presenting the controller:
let next = self.storyboard?.instantiateViewControllerWithIdentifier("SecondViewController") as! SecondViewController
next.ip = ipAddressField.text
next.username = usernameField.text
next.password = passwordField.text
self.presentViewController(next, animated: false, completion: nil)
You can read more about segue here
Updated syntax for Swift 3:
let next = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as? SecondViewController
next.ip = ipAddressField.text
next.username = usernameField.text
next.password = passwordField.text
self.present(next, animated: true, completion: nil)