I am fairly new to Swift programming. Using Userdefaults I was trying to customize user behaviour. Below image is of my initial controller. I require to save userdefaults so that App remembers the user selection of button, (i.e. A or B). Can you assist to provide me a function that I use in viewDidLoad and it remembers the button selection and segues to its respective ViewController.
My code to perfrom segue if Button A or B is selected is
let parent = self.storyboard?.instantiateViewController(withIdentifier: "DashboardVC") as! DashboardVC
self.navigationController?.pushViewController(parent!, animated: true)
Yet it doesnt segue. It keeps loading my initial viewcontroller.
do like
set the tag for each button and create the common method for handle the function , for e.g
#IBAction func handle_Action(_ sender: UIButton) {
defaultName.set(sender.tag, forKey: "yourKeyName")
}
and in your class
class ViewController: UIViewController {
let defaultName = UserDefaults.standard
// finally access the integer in your Viewload
override func viewDidLoad() {
super.viewDidLoad()
let getVal = defaultName.integer(forKey: "yourKeyName") as Int
if getVal == 1{ //called by A
}else if getVal == 2{
//called by B
}else{ // not interactwithButton action }
}
Related
I am trying to transfer my object from HockeyDetailVC to my FavouritesVC using a button but my object is nil when I reach my second VC FavouritesVC. Why is it like that when I set the variable in my firstVC with my func transferObj()?
HockeyDetailVC
var item: CurrentPlayers?
override func viewDidLoad() {
super.viewDidLoad()
gonnaLoadView()
tableV.bounces = false
tableV.alwaysBounceVertical = false
favButton.layer.cornerRadius = 10
print(item) *//prints my current players object*
}
func transferObj() {
let otherVC = FavouritesVC()
otherVC.currentFav = item
print(item). *//prints my current player object*
}
#IBAction func addToFav(_ sender: Any) {
transferObj()
print("Favourite button Pressed")
}
FavouritesVC
var currentFav: CurrentPlayers?
override func viewDidLoad() {
super.viewDidLoad()
if currentFav == nil {
//display nil
self.tableView.separatorStyle = UITableViewCell.SeparatorStyle.none
print(favArr) *//prints empty array*
print(currentFav) *//nil*
} else {
favArr.append(currentFav!)
print(favArr)
}
}
As #Martin stated, let otherVC = FavouritesVC() creates a new instance of the controller, but it is not the instance that you will eventually display. So you are effectively setting the currentFav of a random FavouritesVC that will never actually be displayed, while the one you eventually do navigate to has it's currentFav property still unset.
To set the appropriate FavouritesVC instance, you need to access it in one of several ways (depending on how you present it). If it is through a segue, then you can reference it in the prepare(for segue: sender:) method. (When you create a Cocoa Touch Class file, the below method template is pre-populated. As it states, reference the new view controller using segue.destination.)
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destination.
// Pass the selected object to the new view controller.
}
*/
Alternatively, if you create and present the new view controller programmatically with something like
// 1.
let otherVC = storyboard?.instantiateViewController(withIdentifier: "yourFavouritesVCIdentifier")
// 2.
// 3.
self.show(otherVC, sender: self)
you can insert your otherVC.currentFav = item at line // 2..
I have buttons in the storyboard that I put into a Referencing Outlet Collection. I'm using UITapGestureRecognizer and UILongPressGestureRecognizer for all of these buttons, but how can I print exactly which button gets tapped? Bellow is what I tried but doesn't work. I get an error that says "Value of type 'UILongPressGestureRecognizer' has no member 'tag'." I'm trying to build the button grid for the Minesweeper game. Thank you for your help.
class ViewController: UIViewController {
#IBOutlet var testButtons: [UIButton]! // There are 100 buttons in this array
override func viewDidLoad() {
super.viewDidLoad()
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
// These indexes are just to test how to recognize which button gets pressed
testButtons[0].addGestureRecognizer(testButtonPressed)
testButtons[1].addGestureRecognizer(testButtonPressed)
}
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
print("Test button was pressed")
print(sender.tag) // THIS DOESN'T WORK, BUT CONCEPTUALLY THIS IS WHAT I WANT TO DO
}
This error occurs because UILongPressGestureRecognizer object has no tag property
You can access sender's button in a way like that:
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
guard let button = sender.view as? UIButton else { return }
print(button.tag)
}
I think that the best solution to handle button's actions is to add #IBAction
(you can add it like #IBOutlet with a minor change - set Action connection type)
And then in #IBAction block you cann access all button properties (like tag and others)
instead of using gesture I think it would be better to use #IBAction and connect the buttons With it here is a small example
UILongPressGestureRecognizer which is a subclass of UIGestureRecognizer, can be used only once per button or view. Because UILongPressGestureRecognizer has only a single view property. In your code, it will always be testButtons[1] calling the testPressed action. So you have to first modify the viewDidLoad code like this :-
for button in testButtons {
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
button.addGestureRecognizer(testButtonPressed)
button.addGestureRecognizer(testButtonPressed)
}
Then you can access the button from testPressed like this (I hope you've already set the tag in the storyboard) :-
#objc func testPressed(_ sender: UILongPressGestureRecognizer) {
if sender.state == .began {
if let button = sender.view as? UIButton {
print(button.tag)
}
}
}
You need to set tags before pressing!
On the viewDidLoad() method you must add something like:
testButtons.enumerated().forEach {
let testButtonPressed = UILongPressGestureRecognizer(target: self, action: #selector(testPressed))
testButtonPressed.minimumPressDuration = 0.5
$0.element.addGestureRecognizer(testButtonPressed)
$0.element.tag = $0.offset
}
And when the long press is receiving you need to get a tag from view not from the sender!
print(sender.view?.tag)
Since a gesture recognizer should only be associated with a single view, and doesn't directly support using an identity tag to match it with buttons. When creating an array of buttons for a keyboard, with a single gesture response function, I found it easier to use the gesture recognizer "name" property to identify the associated button.
var allNames: [String] = []
// MARK: Long Press Gesture
func addButtonGestureRecognizer(button: UIButton, name: String) {
let longPrssRcngr = UILongPressGestureRecognizer.init(target: self, action: #selector(longPressOfButton(gestureRecognizer:)))
longPrssRcngr.minimumPressDuration = 0.5
longPrssRcngr.numberOfTouchesRequired = 1
longPrssRcngr.allowableMovement = 10.0
longPrssRcngr.name = name
allNames.append(name)
button.addGestureRecognizer(longPrssRcngr)
}
// MARK: Long Key Press
#objc func longPressOfButton(gestureRecognizer: UILongPressGestureRecognizer) {
print("\nLong Press Button => \(String(describing: gestureRecognizer.name)) : State = \(gestureRecognizer.state)\n")
if gestureRecognizer.state == .began || gestureRecognizer.state == .changed {
if let keyName = gestureRecognizer.name {
if allNames.contains(keyName) {
insertKeyText(key: keyName)
} else {
print("No action available for key")
}
}
}
}
To implement, call the addButtonGestureRecognizer function after creating the button, and provide a name for the button (I used the button text) e.g.
addButtonGestureRecognizer(button: keyButton, name: buttonText)
The button name is stored in the "allNames" string array so that it can be matched later in "longPressOfButton".
When the button name is matched in the "longPressOfButton" response function, it passes it to "addKeyFunction" where it is processed.
I’m creating a weightlifting calculator application (Swift 4) using MVVM and have been trying for 2 days to figure out why a view model that should have died is still responding to a UserDefaults.defaultsDidChange event notification.
I launch the app:
At launch, in the AppDelegate, I create a new lift event object and use it to initialize a new CalculatorLiftEventViewModelFromLiftEvent for the `CalculatorViewController':
I calculate a lift and save it
I tap the + button to create a new lift:
this causes a new, empty lift event object to be created
this new lift event object is used to initialize a new CalculatorLiftEventViewModelFromLiftEvent object
this new CalculatorLiftEventViewModelFromLiftEvent is then assigned to the CalculatorViewController's viewModel property, replacing the one created when the app launched
the values on the calculator screen are zeroed out, ready for a new lift event to be entered
I tap the Settings button to go to Settings where I change the Formula associated with the current lift event.
The new Formula is saved as the default and the UserDefaults.defaultsDidChange notification is fired
HERE’S THE PART I CAN’T FIGURE OUT: the original view model is still alive and it’s still listening for UserDefault notifications. When I close the Settings screen and go back to the Calculator view, the values from the prior lift event that had been cleared out now reappear.
Here’s what happens when the + (new) button on the Calculator screen is tapped:
#objc fileprivate func onNewButtonTapped(_ sender: UIBarButtonItem) {
let newLiftEvent = dataManager.createNewLiftEvent()
viewModel = CalculatorLiftEventViewModelFromLiftEvent(withLiftEvent: newLiftEvent, dataManager: dataManager)
setupView()
}
Here’s how the CalculatorLiftEventViewModelFromLiftEvent is initialized:
init(withLiftEvent liftEvent: LiftEventRepresentable, dataManager: CoreDataHelper) {
self.modelLiftEvent = liftEvent
self.liftName = Dynamic("\(modelLiftEvent.lift.liftName)")
self.weightLiftedTextField = Dynamic(modelLiftEvent.liftWeight.value)
self.repetitionsTextField = Dynamic("\(modelLiftEvent.repetitions)")
self.oneRepMaxTextField = Dynamic(modelLiftEvent.oneRepMax.value)
self.unitsTextField = Dynamic("\(UserDefaults.weightUnit())")
self.weightPercentages = Dynamic( [ : ] )
self.dataManager = dataManager
super.init()
subscribeToNotifications()
}
UPDATE: Here are the deinit and the addObservers in CalculatorLiftEventViewModelFromLiftEvent. Notice I'm not using block-based observations.
deinit {
print("I got to the deinit method")
unsubscribeFromNotifications()
}
func subscribeToNotifications() {
NotificationCenter.default.addObserver(self,
selector: #selector(liftNameDidChangeNotification(_:)),
name: NSNotification.Name(rawValue: LiftEventNotifications.LiftNameDidChangeNotification),
object: nil)
NotificationCenter.default.addObserver(self,
selector: #selector(weightUnitDidChangeNotification(_:)),
name: NSNotification.Name(rawValue: LiftEventNotifications.WeightUnitDidChangeNotification),
object: nil)
NotificationCenter.default.addObserver(self,
selector: #selector(roundingOptionDidChangeNotification(_:)),
name: NSNotification.Name(rawValue: UserDefaultsNotifications.roundingOptionDidChangeNotification),
object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.defaultsDidChange), name: UserDefaults.didChangeNotification,
object: nil)
}
--- END UPDATE
I pass the modelLiftEvent when segueing to the SettingsViewController:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let identifier = segue.identifier {
switch identifier {
case a:...
case b:...
case "SettingsSegue":
if let nav = segue.destination as? UINavigationController {
let destinationViewController = nav.topViewController as! SettingsViewController
destinationViewController.dismissalDelegate = self
let settingsViewModel = SettingsViewModelFromLiftEvent(withLiftEvent: self.viewModel.modelLiftEvent)
destinationViewController.settingsViewModel = settingsViewModel
destinationViewController.dataManager = dataManager
settingsViewModel.dataManager = dataManager
}
Finally, in CalculatorLiftEventViewModelFromLiftEvent, I’ve put a break point here because this is called when the view model hears the UserDefaults.defaultsDidChange notification. At this point, I have also verified that this CalculatorLiftEventViewModelFromLiftEvent is the old one, not the new one created when I tapped the + button:
#objc func defaultsDidChange(_ notification: Notification) {
let oneRepMax = modelLiftEvent.calculateOneRepMax()
guard oneRepMax.value != 0.0 else { return }
let weightPercentages = getWeightPercentages(weight: oneRepMax.value)
self.weightPercentages.value = weightPercentages
weightLiftedTextField.value = modelLiftEvent.liftWeight.value
repetitionsTextField.value = "\(modelLiftEvent.repetitions)"
oneRepMaxTextField.value = modelLiftEvent.oneRepMax.value
}
I've read through a bunch of documentation about the life cycle of objects but haven't found anything that helps. I expect that when the new CalculatorLiftEventViewModelFromLiftEvent is created and assigned to the `CalculatorViewController''s viewModel property, it would replace the reference to the old one and it would cease to exist. Evidently, that's not what's happening.
Does anyone have any idea why when I go from the Calculator view (step 3) that has no values (except for 0.0) to the Settings and then come back, the prior lift event values are displayed?
I've fixed the problem of the prior liftEvent being displayed after clearing the calculator, changing the default formula, and coming back to the calculator screen.
On CalculatorViewController, when the + button is tapped, instead of creating a new viewModel and assigning it to the viewModel property, I'm asking my AppDelegate to create both a new CalculatorViewController and CalculatorLiftEventViewModelFromLiftEvent by using the launchCalculatorViewController method which does this when the app launches.
The original code in CalculatorViewController:
#objc fileprivate func onNewButtonTapped(_ sender: UIBarButtonItem) {
let newLiftEvent = dataManager.createNewLiftEvent()
viewModel = CalculatorLiftEventViewModelFromLiftEvent(withLiftEvent: newLiftEvent, dataManager: dataManager)
self.percentagesTableView.reloadData()
setupView()
}
Now the new code in CalculatorViewController:
#objc fileprivate func onNewButtonTapped(_ sender: UIBarButtonItem) {
(UIApplication.shared.delegate as? AppDelegate)?.launchCalculatorViewController()
}
and in AppDelegate:
func launchCalculatorViewController() {
self.window = UIWindow(frame: UIScreen.main.bounds)
let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
if let initialViewController: CalculatorViewController = mainStoryboard.instantiateInitialViewController() as? CalculatorViewController {
self.window?.rootViewController = initialViewController
let liftEvent = dataManager.createNewLiftEvent()
let viewModel = CalculatorLiftEventViewModelFromLiftEvent(withLiftEvent: liftEvent, dataManager: dataManager)
initialViewController.viewModel = viewModel
initialViewController.dataManager = dataManager
self.window?.makeKeyAndVisible()
}
}
Unfortunately, I determined that CalculatorLiftEventViewModelFromLiftEvent objects are never being deallocated which tells me I've got a strong reference cycle that won't let go:
That will have to be another SO question.
I am working on an iOS application that is built around a Tab View Controller. I have created a "Contacts" tab, where a user can find and select a contact from a list. When the user selects the contact, it takes the contact's name and passes it to a different tab. That function is being done like so:
func passName(name: String) {
let navTab = self.tabBarController!.viewControllers![2] as! UINavigationController
let homeTab = navTab.viewControllers[0] as! MainController
homeTab.passedName = name
tabBarController?.selectedIndex = 2
}
Everything works as it should so far (name is loaded into text field). My issue is that the value seems to keep coming back every time I change tabs and then go back to my Home tab. For example, if I select "John" from my contacts, it will take me to the Home Tab and put John's name in a textfield. Let's say I delete the last two letters of the name, so now it is "Jo". If I load a different tab and come back, the name field has been reset to "John". It's as if the value gets re-passed every time I open the Home Tab. Also, every time I load the Home Tab after passing a name, my console prints: "Name Passed: John", so it shows that this is being processed every single time the tab appears. Here is my code for processing the name:
var passedName: String!
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
//Checks if name was passed to controller
if let validName = passedName {
print("Name passed: \(validName)")
nameTextField.text = validName
}
}
Am I passing the data incorrectly? I was thinking it might be because I have the above code being called in the viewWillAppear method, but that doesn't make sense, as essentially the data is only being passed one time from the Contacts tab. Thanks!
The problem is that you're not actually passing the value back to the original view. Apple's recommendation for passing information between classes is to use the delegate pattern. This allows the modal view to call the delegate class's function, which changes the name local to the original view because that function is declared in the original view's viewController. You can read more about the pattern in this tutorial, but I've also included a brief example relevant to your use case below.
mainViewController:
class namesTableViewController: UITableViewController, editNameDetailsViewControllerDelegate {
var name : String
#IBAction func editButtonPressed(_ sender: UIBarButtonItem) {
performSegue(withIdentifier: "editPerson", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "editPerson" { //Modal segue
let navController = segue.destination as! UINavigationController
let controller = navController.topViewController as! editNameViewController
controller.delegate = self
if let person = sender as? Person {
print("Sending person to edit")
controller.personToEdit = person
}
} else {
super.prepare(for: segue, sender: sender)
}
}
//Protocol function
func changeName(n: String, controller: UIViewController) {
name = n
dismiss(animated: true, completion: nil)
}
}
editNameViewController:
class editNameViewController: UIViewController {
#IBOutlet weak var personNameTextField: UITextField!
var personToEdit : Person?
weak var delegate : PersonTableViewController?
override func viewDidLoad() {
super.viewDidLoad()
if personToEdit != nil {
personNameTextField.text = personToEdit?.name
}
}
// Button Actions
#IBAction func saveButtonPressed(_ sender: UIBarButtonItem) {
delegate?.personDetailsView(n: personNameTextField.text, controller: self)
}
}
Finally, the protocol class :
protocol editNameDetailsViewControllerDelegate : class {
func personDetailsView(n: String, controller: UIViewController)
}
Hope this helps.
The problem is "passedName" variable doesn't changed its value every time you edit it in your UITextField. Keep in mind that every time you change tabs, the UIViewController will call viewWillAppear and viewDidAppear. So your UITextField will always show passedName value once you select other tab and return.
I suggest that every time you edit the textfield you should update passedName value.
Sorry for my bad english.
In my program when a button is pressed I am adding information to a database, including creating invoice number then calling a segue to a new view controller. When the new view controller is called I'd like to pass along that invoice number. Everything works fine, I can pass along sample data no problem. However, it appears that "override func prepareForSegue(segue: NSStoryboardSegue, sender: AnyObject!) {}" is being called before my button (upon initialization of the view controller?), so I am passing along a blank value. How can I make my prepareForSegue wait till after my button is pressed? Here is the code I currently have.
#IBAction func createInvoice(sender: AnyObject) {
let realm = Realm()
let invoicepull = Invoice()
let invoicecount = realm.objects(Invoice)
let invoicenraw = invoicecount.count
let a = 100
let invoicenumber = a + invoicenraw
var invoicefile = Invoice()
invoicefile.inumber = invoicenumber
invoicefile.cnumber = clientcombo.stringValue
invoicefile.cost = owed.doubleValue
invoicefile.paid = paid.doubleValue
invoicefile.sevicecode = service.stringValue
invoicefile.dateofservice = NSDate()
// Save your object
realm.beginWrite()
realm.add(invoicefile)
realm.commitWrite()
//Sent notification
performSegueWithIdentifier("cinvoiceseuge", sender: nil)
println("Inside Action")
println(invoicenumber)
dismissViewController(self)
}
override func prepareForSegue(segue: NSStoryboardSegue, sender: AnyObject!) {
if (segue.identifier == "cinvoiceseuge") {
//Checking identifier is crucial as there might be multiple
// segues attached to same view
var detailVC = segue.destinationController as! invociegenerator;
detailVC.toPass = invoicenumber
println("Inside Sugue")
println(invoicenumber)
}
}
Update: I belive this is an issue with the Realm database causing it to behave unexpectedly. If I remove all realm code, the program works as expected and I can pass a static dummy value.
invoicenumber in createInvoice() is a local variable and invoicenumber in prepareForSegue() seems to be an instance variable. is it what you expected?