I have a UIView set to hidden on a View Controller (product menu), then the user clicks on a product via tableview cell. When they hit return to the initial View Controller I want to make the UIView in the first VC visible.
When I use the code below I get the error: Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
{
//First View Controller
#IBOutlet weak var basketView: UIView!
.
.
self.basketView?.isHidden = true
//Second View Controller
#IBAction func returnBtn(_ sender: UIButton) {
let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let menuCV = storyBoard.instantiateViewController(withIdentifier: "MenuViewController") as! MenuViewController
menuCV.basketView.isHidden = false
self.present(menuCV, animated: true, completion: nil)
}
}
You can't access any outlet before the vc is presented/loaded as i'll be nil so
Option 1
menuCV.loadViewIfNeeded()
menuCV.basketView.isHidden = false
Option 2
Add a bool value
menuCV.hideBasket = false
Then set this inside viewDidLoad of MenuViewController
self.basketView.isHidden = hideBasket
Related
I have a UITabBarController with 3 tabs and a SettingsVC where you can choose the appearance of MainVC (There are 2 different ViewControllers which based on what user prefers should be shown as the MainVC).
I made the application and it works but it's really buggy, cause I was just pushing the ViewControllers on top of each other, and in some certain conditions you see bugs while switching tabs.
Main.storyboard
Here is some part of my code(after trying a lot of stuff) which changes the VC's based on UserDefaults
CheckSettingsStatus.swift
//
// Check for Double Column Settings and navigate to Double Column VC
//
func checkMainVCViewStatusAndNavigateAcordingly(){
if UserDefaults.standard.integer(forKey: KEY_MAIN_VC_VIEW) == 1{
//let appDel = UIApplication.shared.delegate as! AppDelegate
//appDel.goToDoubleMainVC()
let mainVC = storyboard?.instantiateViewController(withIdentifier: "DoubleColumnMainVC") as! DoubleColumnMainVC
self.navigationController?.viewControllers[0] = mainVC
//navigationController?.pushViewController(mainVC, animated: false)
var navigationArray = self.navigationController?.viewControllers
print("Number of VCs = \(String(describing: navigationArray?.count))")
if navigationArray?.count == nil{
self.navigationController?.pushViewController(mainVC, animated: false)
}else{
self.navigationController?.popToRootViewController(animated: false)
}
// self.navigationController?.viewControllers = navigationArray!
}
}
//
// same as function above but goes to MainVC
//
func checkDoubleColumnMainVCViewStatusAndNavigateAcordingly(){
if UserDefaults.standard.integer(forKey: KEY_MAIN_VC_VIEW) == 0{
// let appDel = UIApplication.shared.delegate as! AppDelegate
// appDel.goToMainVC()
let mainVC = storyboard?.instantiateViewController(withIdentifier: "MainVC") as! MainVC
self.navigationController?.viewControllers[0] = mainVC
var navigationArray = self.navigationController?.viewControllers
print("Number of VCs = \(String(describing: navigationArray?.count))")
if navigationArray?.count == nil{
navigationController?.pushViewController(mainVC, animated: false)
}else{
self.navigationController?.popToRootViewController(animated: false)
}
// self.navigationController?.viewControllers = navigationArray!
}
}
With this in ViewWillAppear of both this Controllers I call these functions to switch accordingly.
Any ideas what I'm doing wrong? Can I push controllers from UITabBarController and not NavigationController? something like:
tabBarController.pushViewController(mainVC, animated: false)
instead of:
navigationController.pushViewController(mainVC, animated: false)
Thank you in advance
UPDATE:
In my best case when everything works nicely, on first launch of the app (to the second mainVC) the Buttons in NavBar doesn't work.
EDIT:
I just realised that the NavigationBar that I'm seeing above my SecondMainVC is the NavigationBar from MainVC, that is why the buttons are not working. how is that possible?
I faced same issue while trying to develop a tab bar controller in storyboard , for this reason I found that the best way is to implement it by code.
so you can make your code look like this :
1) create a a sub class of UITabController and let it conform to UITabBarControllerDelegate
class TabBarVC: UITabBarController , UITabBarControllerDelegate {
2)then write this method in your class to initialize the tabs in your project:
private func settingUpTabBarAndInitializingViewControllers(){
//self delagting
self.delegate = self
//home tab
let homeStoryboard = UIStoryboard(name: Constants.StoryBoards.homeStoryboard, bundle: nil)
let homeVC = homeStoryboard.instantiateViewController(withIdentifier: Constants.ControllersIDs.homeScreen) as! HomeVC
// shop tab
let shopStoybaord = UIStoryboard(name: Constants.StoryBoards.shopStoryboard, bundle: nil)
let shopVC = shopStoybaord.instantiateViewController(withIdentifier: Constants.ControllersIDs.shopScreen) as! ShopVC
//offers tab
let offersStoryboard = UIStoryboard(name: Constants.StoryBoards.offersStoryboard, bundle: nil)
let offersVC = offersStoryboard.instantiateViewController(withIdentifier: Constants.ControllersIDs.offersScreen) as! OffersVC
//more tab
let moreStoryboard = UIStoryboard(name: Constants.StoryBoards.MoreScreenStoryboard, bundle: nil)
let moreVC = moreStoryboard.instantiateViewController(withIdentifier: Constants.ControllersIDs.moreVCScreen) as! MoreOptionsTVC
//setting VCs
self.viewControllers = [homeVC , shopVC , offersVC , moreVC]
//setting buttons
//buttons images
let homeImage = UIImage(named: "TabHome")
let shopImage = UIImage(named : "TabShop")
let offerImage = UIImage(named: "TabOffers")
let moreImage = UIImage(named: "TabMenu")
// buttons shakhsiyan
let homeButton = UITabBarItem(title: homeText, image: homeImage, selectedImage: homeTappedImage)
let shopButton = UITabBarItem(title: shopText, image: shopImage, selectedImage: shopTappedImage)
let offersButton = UITabBarItem(title: offersText, image: offerImage, selectedImage: offersTappedImage)
let moreButton = UITabBarItem(title: moreText, image: moreImage, selectedImage: moreTappedImage)
homeVC.tabBarItem = homeButton
shopVC.tabBarItem = shopButton
offersVC.tabBarItem = offersButton
moreVC.tabBarItem = moreButton
}
P.S. you can add tabs as much as you want and while scrolling in them you wont face any bug,
make sure to have only one navigation controller before your tab bar controller.
Check this hope it helps
Ok you can create a DEMO to see how thing works.After that you can implement it in your project.I know it may not look good to you but read it once and see image attached i am sure will get your answer.
1.I have created two UIViewControllers with the UITabBarController.
2.I have created class ItemFirstVC,ItemTwoVC and assigned to UIViewControllers in storyboard
3.Each controller is embedded in UINavigationController
4.Create a custom class of UITabBarController
5.Assign it to UITabBarController in storyboard
6.Now Each UIViewController has a button named as Firs Button,Second Button
7.From each button i have connected Action Segue to one more controller as you can see in image.
8.Now i have created a third UIViewController which is separate from UITabBarController.
9.Now we will load that Third UIViewController in UITabBarController
10.Create one more class ItemThirdVC and assign it to third UIViewController.
11.It also has a button named as third button action segued to one more UIViewController
12.Now switch to custom class of UITabBarContoller
// variable required to see work in action
var count = 0
class CustomTabBarController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
// remember to assign delegate
delegate = self
}
// this delegate indicates whether this tab should be selected or not
extension CustomTabBarController : UITabBarControllerDelegate{
func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
// switch to UIViewController tabs multiple times
count = count + 1
if(count == 5){
// when count reaches 5 a new controller will load
let navigationController = viewController as? UINavigationController
guard navigationController != nil else {return true}
let viewController = storyboard?.instantiateViewController(withIdentifier: "ItemThreeVC")
guard let vc = viewController else {return true}
navigationController?.setViewControllers([vc], animated: false)
}
return true
}
}
In the project shown below there is an InitialViewController that has a single button labeled "Show Popover". When that button is tapped the app is supposed to present the second view controller (PopoverViewController) as a popover. The second view controller just has a label saying "Popover!".
This works fine if the InitialViewController takes care of instantiating PopoverViewController, retrieving the popoverPresentationController and then setting the popoverPresentationController's delegate to itself (to InitialViewController). You can see the result, below:
For maximum reusability, however, it would be great if the InitialViewController did not need to know anything about how the presentation controller is delegated. I think it should be possible for the PopoverViewController to set itself as the popoverPresentationController's delegate. I've tried this in either the viewDidLoad or the viewWillAppear functions of the PopoverViewController. However, the PopoverViewController is presented modally in both cases, as shown below:
All the code is contained in just the InitialViewController and the PopoverViewController. The code used in the failing version of the InitialViewController is shown below:
import UIKit
// MARK: - UIViewController subclass
class InitialViewController: UIViewController {
struct Lets {
static let storyboardName = "Main"
static let popoverStoryboardID = "Popover View Controller"
}
#IBAction func showPopoverButton(_ sender: UIButton) {
// instantiate & present the popover view controller
let storyboard = UIStoryboard(name: Lets.storyboardName,
bundle: nil )
let popoverViewController =
storyboard.instantiateViewController(withIdentifier: Lets.popoverStoryboardID )
popoverViewController.modalPresentationStyle = .popover
guard let popoverPresenter = popoverViewController.popoverPresentationController
else {
fatalError( "could not retrieve a pointer to the 'popoverPresentationController' property of popoverViewController")
}
present(popoverViewController,
animated: true,
completion: nil )
// Retrieve and configure UIPopoverPresentationController
// after presentation (per
// https://developer.apple.com/documentation/uikit/uipopoverpresentationcontroller)
popoverPresenter.permittedArrowDirections = .any
let button = sender
popoverPresenter.sourceView = button
popoverPresenter.sourceRect = button.bounds
}
}
The code in the failing PopoverViewController is shown below:
import UIKit
// MARK: - main UIViewController subclass
class PopoverViewController: UIViewController {
// MARK: API
var factorForMarginsAroundButton: CGFloat = 1.2
// MARK: outlets and actions
#IBOutlet weak var popoverLabel: UILabel!
// MARK: lifecycle
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear( animated )
// set the preferred size for popover presentations
let labelSize =
popoverLabel.systemLayoutSizeFitting( UILayoutFittingCompressedSize )
let labelWithMargins =
CGSize(width: labelSize.width * factorForMarginsAroundButton,
height: labelSize.height * factorForMarginsAroundButton )
preferredContentSize = labelWithMargins
// set the delegate for the popoverPresentationController to self
popoverPresentationController?.delegate = self
}
}
// MARK: - UIPopoverPresentationControllerDelegate
// (inherits from protocol UIAdaptivePresentationControllerDelegate)
extension PopoverViewController: UIPopoverPresentationControllerDelegate
{
func adaptivePresentationStyle(for controller: UIPresentationController,
traitCollection: UITraitCollection)
-> UIModalPresentationStyle{
return .none
}
}
Is it possible for a view controller that is being presented as a popover to be the delegate for its own popoverPresentationController?
I'm using Xcode 8.0, Swift 3.1 and the target is iOS 10.0
It's certainly possible. You're dealing with a timing issue. You need to set the delegate before viewWillAppear. Unfortunately, there is no convenient view lifecycle function to insert the assignment into, so I did this instead.
In your PopoverViewController class, assign the delegate in an overriden getter. You can make the assignment conditional if you'd like. This creates a permanent relationship, so other code code never "override" the delegate by assigning it.
override var popoverPresentationController: UIPopoverPresentationController? {
get {
let ppc = super.popoverPresentationController
ppc?.delegate = self
return ppc
}
}
As #allenh has correctly observed, you need to set the delgate before viewWillAppear, and he has offered a clever solution by setting the delegate by overriding the popoverPresentationController getter.
You could also set the delegate to the popover itself in your showPopover() function between setting modalPresentationStyle and presenting the popover:
let vc = storyboard.instantiateViewController(withIdentifier: Lets.popoverStoryboardID )
vc.modalPresentationStyle = .popover
vc.popoverPresentationController?.delegate = vc
present(vc, animated: true, completion: nil)
I am currently creating a login project in Swift 3.
I have a main view controller which contains
a container, which includes a page viewcontroller and multiple pages
a custom "menu" at the bottom which includes two buttons for navigating the page view controller and a custom page control
This is my storyboard setup
The view the user will be presented with is made of the pages controlled by the page viewcontroller, at the top, and the control menu, at the bottom. When the user clicks on the buttons in the control menu this code will be executed in the main viewcontroller:
#IBAction func buttonNext(_ sender: UIButton) {
print("buttonNext has been pressed!")
nextPageWithIndex(index: nextIndex)
}
and here is the function it calls:
func nextPageWithIndex(index: Int) {
let nextWalkthroughVC = pages[index]
pageContainer.setViewControllers([nextWalkthroughVC], direction: .forward, animated: true, completion: nil)
print("nextPageWithIndex has been executed with Index \(index)!")
if currentIndex as Int? == 2 {
currentIndex = 2
} else if currentIndex as Int? == 1 {
currentIndex = 2
} else if currentIndex as Int? == 0 {
currentIndex = 1
} else {
currentIndex = 0
print("currentIndex was in inpossible state!")
}
checkButtonNavigation()
assignIndexes()
if let index = currentIndex {
pageControl.currentPage = index
print("PageControl updated")
}
}
checkButtonNavigation() checks if the buttons at the bottom should be displayed depending on the page which is currently being displayed.
I am trying to implement a button of one of the pages (in this case page1) which navigates the user to the next page.
I tried to execute the function nextPageWithIndex(index: 1) with varAccountRegisterMainViewController.nextPageWithIndex(index: 1) on the action of pressing the button in the page1 viewcontroller class by defining:
var varAccountRegisterMainViewController: accountRegisterMainViewController!
in the AppDelegate,
and:
varAccountRegisterMainViewController = accountRegisterMainViewController()
in the page1 viewcontroller.
Sadly that doesn't seem to work. I get "fatal error: Index out of range" at the point:
let nextWalkthroughVC = pages[index]
in the function nextPageWithIndex(index: 1) in the main viewcontroller. I checked what count the array "pages" has. It's 0. When I execute the function right from the main viewcontroller, though, it has 3 as it should have. Here is the error as an image.
Thank you for your help!
EDIT:
here is how the pages Array is set-up:
At the beginning of the main viewcontroller class the following code is added:
var pages = [UIViewController]()
In the viewDidLoad() that code:
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let page1: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage1ViewController")
let page2: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage2ViewController")
let page3: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage3ViewController")
pages.append(page1)
pages.append(page2)
pages.append(page3)
ANOTHER EDIT:
I put the declaration of "pages" also into the externalNext() function. Now that problem is solved but there is another one... this is how the function looks now:
func externalNext(index: Int) {
var pageContainer: UIPageViewController!
var pages = [UIViewController]()
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let page1: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage1ViewController")
let page2: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage2ViewController")
let page3: UIViewController! = storyboard.instantiateViewController(withIdentifier: "IDAccountRegisterPage3ViewController")
pages.append(page1)
pages.append(page2)
pages.append(page3)
// Create the page container
pageContainer = UIPageViewController(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)
pageContainer.delegate = self
pageContainer.dataSource = self
pageContainer.setViewControllers([page1], direction: UIPageViewControllerNavigationDirection.forward, animated: false, completion: nil)
// Add it to the view
view.addSubview(pageContainer.view)
pageContainer.view.addSubview(pageControlView)
print("Current array count of pages is \(pages.count)")
print("Function: nextPageWithIndex has been called with index \(index)")
let nextWalkthroughVC = pages[index]
pageContainer.setViewControllers([nextWalkthroughVC], direction: .forward, animated: true, completion: nil)
print("nextPageWithIndex has been executed with Index \(index)!")
pageControl.currentPage = index
print("PageControl updated")
print("Hello")
}
I copied the code from the top of the main viewcontroller class and just pasted it into the function. I alway get the error "fatal error: unexpectedly found nil while unwrapping an Optional value", though.
Is there any way I can redefine the objects in the function?
Or is there any elegant way? My way looks very messy...
Thanks to Phillip Mills I know that is has something to do with being another instance of the class main viewcontroller. How can I access the function in there but within the same instance? The main viewcontroller is visible all the time.
Thank you!
When you do this: accountRegisterMainViewController() you are creating a new object, a different instance of that class. Since the new one is not being displayed, viewDidLoad is never called and your array is empty.
You need to arrange links between objects so that the one loaded from your storyboard is also the one that nextPageWithIndex is called on.
I'm quite new with Swift and I'm making this mini game type app that counts the score and updates the label in the view controller. I want to pass that score from a view controller into another external pop up view controller I created.
#IBAction func Button7Tapped(_ sender: AnyObject)
{
if Index == 13 {
game.score += 1
} else {
let scorepopVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "finalScorePop") as! finalScoreViewController
self.addChildViewController(scorepopVC)
scorepopVC.view.frame = self.view.frame
self.view.addSubview(scorepopVC.view)
scorepopVC.didMove(toParentViewController: self)
}
updateGame()
}
Above is my code for the external pop up view controller I created, which also has a separated .swift file. How would I go about taking my game.score and passing that into my Popup view controller?
In your finalScoreViewController swift file add a new property.
final class FinalScoreViewController: UIViewController {
var score: Int?
}
And then just assign it when you're instantiating it.
#IBAction func Button7Tapped(_ sender: AnyObject) {
if Index == 13 {
game.score += 1
} else {
let scorepopVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "finalScorePop") as! finalScoreViewController
scorepopVC.score = game.score //THIS LINE
self.addChildViewController(scorepopVC)
scorepopVC.view.frame = self.view.frame
self.view.addSubview(scorepopVC.view)
scorepopVC.didMove(toParentViewController: self)
}
updateGame()
}
It is better to use storyboard to open the ViewController. In storyboard, right click and drag from you button to the second view controller (the one that you wish to open).
Choose the segue type that you wish to use. In your case, I think Present Modally will work fine.
You will see a line between the two UIViewControllers in storyboard. That is the segue. Tap on it. In the Attributes inspector give the segue an identifier. For instance "myFirstSegue".
Then in the code of the UIViewController that contains your button override prepare(for:sender:). This method is called when preparing for the segue to happen. I.o.w when you tap on the button. You have access to the destination UIViewController and can therefor access and set the properties on it.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "myFirstSegue" {
if let vc = segue.destination as? MyViewController {
//here you set your data on the destination view controller
vc.myString = "Hello World"
}
}
}
Note that we check the identifier, because all segues that go from this ViewController to other ViewControllers will call prepare(for:sender:)
It's quite simple, Just add a property in your finalScoreViewController (if you are not already done this) and -for example- call it score:
class finalScoreViewController: UIViewController {
var score: String?
// ...
Add this line to the Button7Tapped action (where you set a value for finalScoreViewController's score):
let scorepopVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "finalScorePop") as! finalScoreViewController
// add this line:
scorepopVC.score = "My score"
self.addChildViewController(scorepopVC)
scorepopVC.view.frame = self.view.frame
self.view.addSubview(scorepopVC.view)
scorepopVC.didMove(toParentViewController: self)
Finally, in finalScoreViewController:
override func viewDidLoad() {
super.viewDidLoad()
if let scr = score {
print(scr)
}
}
Hope that helped.
You do not actually have to pass the variable to the next view controller. All you have to do is create a variable outside of the View Controller class, and voila, you can access your variable from anywhere, in any swift file. For example:
var score = 0
class ViewController: UIViewController {
override func viewDidLoad(){
super.viewDidLoad()
}
#IBAction func Button7Tapped(_ sender: AnyObject){
score += 1
}
}
And then in the other View Controller, you would have something like this:
#IBOutlet weak var scoreLabel: UILabel!
class ViewController: UIViewController {
override func viewDidLoad(){
super.viewDidLoad()
var timer1 = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updateScore), userInfo: nil, repeats: true)
}
#objc func updateScore() {
scoreLabel.text = "You have \(score) points!"
}
I have a UISplitViewController in my iOS app, but my initial view controller is a normal UIViewController.
I want to open the UISplitViewController when a button is clicked on the UIViewController:
#IBAction func openSplitViewController(sender: AnyObject) {
let splitViewController = UISplitViewController()
let leftNavController = splitViewController.viewControllers.first as! UINavigationController
let masterViewController = leftNavController.topViewController as! MenuTableViewController
let rightNavController = splitViewController.viewControllers.last as! UINavigationController
let detailViewController = rightNavController.topViewController as! DetailViewController
splitViewController.viewControllers = [masterViewController,detailViewController];
self.presentViewController(splitViewController, animated: true, completion: nil)
}
But when I click the button, I get:
fatal error: unexpectedly found nil while unwrapping an Optional value
How should I be opening the UISplitViewController from the UIViewController?
Your error has nothing to do with a UISplitViewController, the error you get is because one or more of your arguments is nil.
So make sure that all of the viewControllers you create are real and not nil.
Look for instance at this line:
let leftNavController = splitViewController.viewControllers.first as! UINavigationController
At this point your splitViewController has no viewControllers assigned, so leftNavController will be nil. You will need to create the navController and viewController before adding them to your splitViewController.