I'm a beginner. I am doing a popover when a button is pressed which then instantiates another view controller where the user can select from 5 choices. I want to be able to save the sender.tag of the button from the first view controller (where code snippet below came from) and pass it to the second where I can save them together to Parse. I'm not using a segue so I can't pass it that way. Thanks in advance!
func showPopover(sender: UIButton) {
let vc = self.storyboard?.instantiateViewControllerWithIdentifier("SelectionViewController")
vc!.modalPresentationStyle = .Popover
vc!.preferredContentSize = CGSizeMake(150, 30)
if let presentationController = vc!.popoverPresentationController {
presentationController.delegate = self
presentationController.permittedArrowDirections = .Up
presentationController.sourceView = self.view
presentationController.sourceRect = sender.frame
self.presentViewController(vc!, animated: true, completion: nil)
}
}
The easiest way would be to declare a variable var myVariable = Int() outside of either view controller class. Then, inside of your main VC and before you instantiate the popover, save the tag to the variable. You'll be able to use it inside the popover.
You could just use a segue (why aren't you?)
You put a property for the tag in the popover and set it in the first view controller, inside
func prepareForSegue(_ segue: NSStoryboardSegue, sender sender: AnyObject?).
To perform the segue, you just use
func performSegueWithIdentifier(_ identifier: String, sender sender: AnyObject?)
, inside your function
func showPopover(sender: UIButton)
If you don't want to use a segue you can simply cast the controller you get from instantiateViewControllerWithIdentifier() to your subclass.
Swift 2.0
func showPopover(sender: UIButton) {
guard let vc = self.storyboard?.instantiateViewControllerWithIdentifier("SelectionViewController") as? MYViewController
} else {
print("This is not the view controller you were looking for..."
return
}
vc.myVariableName = sender.tag
...
}
Related
I've set up a simple Swift project to try and wrap my head around delegates & protocols. The goal is to pass data between two classes (SendingClass & ReceivingClass). Two buttons in the SendingClass are linked to the delegate which should trigger the Protocol conforming function in the ReceivingClass to execute. This doesn't work unfortunately, I suspect it has to do with where and how I am declaring the ReceivingClass as the delegate.
Appreciate your insights, i'm just starting out!
I've tried setting the delegate in various locations (presently within viewDidLoad, but cant get it to work).
let vc = SendingClass()
vc.statusDelegate = self
SendingClass.swift
import UIKit
protocol StatusDelegate {
func statusChanged(state: Bool, sender: String)
}
class SendingClass: UIViewController {
var statusDelegate : StatusDelegate?
#IBAction func button1Pressed(_ sender: UIButton) {
statusDelegate?.statusChanged(state: true, sender: "Button 1")
}
#IBAction func button2Pressed(_ sender: UIButton) {
statusDelegate?.statusChanged(state: false, sender: "Button 2")
}
}
ReceivingClass.swift
import Foundation
import UIKit
class ReceivingClass: UIViewController, StatusDelegate {
override func viewDidLoad() {
let vc = SendingClass()
vc.statusDelegate = self
}
func statusChanged(state: Bool, sender: String) {
print("Sender = \(sender) , State = \(state)")
}
}
Expected: the ReceivingClass protocol conforming function (func statusChanged) should execute each time the buttons are pressed within the SendingClass.
Actual: Nothing happens
I am using this..
// create extension in your receiving class
extension ReceivingClass: PopUpVCDelegate {
func statusChanged(state: Bool, sender: String) {
print("Sender = \(sender) , State = \(state)")
}
}
// on sending class, when you present your receiving class on any button click
eg.
let resultController = self.storyboard?.instantiateViewController(withIdentifier: "PopUpVCID") as? PopUpVC
resultController?.delegate = self
self.present(resultController!, animated: true, completion: nil)
//or if not have button add on viewdidload in receiving class
// here is full eg
How to get data from popup view controller to custom table view cell?
For protocol and delegate, you use it when u want to bring a value from 2nd VC (presented by 1st or pushed by 1st VC) to 1st VC, which is the original.
From your code, I dont see you presenting or pushing your 2nd VC. that's why it's not working. Hopefully I answered your doubt.
However if you still want to bring a value over from 1st VC to 2nd VC. In second VC, create a variable to receive it
var ReceivedData = String()
then from your first VC, when u are going to push it,
let vc = SendingClass()
vc.ReceivedData = "Whatever you want it to receive"
If you're using storyboard segues, maybe the view controller is instantiated from there so probably you have to use the prepareForSegue and get the destination view controller (which is already instantiated for you) in the ReceivingClass view controller:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
if let destination = segue.destination as? SendingClass {
destination.delegate = self
}
}
Also be careful with delegate patter: the delegate property should be declared as a weak property to avoid retain-cycle
weak var delegate: MyDelegate?
I have a Tabbed App with two tabs... the first tab has the main Action, and the second has Settings that can be updated. I am trying to pass some variables data from Settings to the Action tab. Based on some suggestions, I have used the following code for the Update button:
#IBAction func updateBut(_ sender: Any) {
let myVC = self.storyboard?.instantiateViewController(withIdentifier: "FirstViewController") as! FirstViewController
myVC.totTime = totalTime
myVC.timeInt = intTime
self.present(myVC, animated: true, completion: nil)
}
The data does pass to the first view controller, however, the tabs have disappeared on this view now. So, how can I get the tabs back on the screen? I am quite the beginner to any form of app development, and am just trying to learn by doing... the Tabbed App has been created using one of the Xcode New Project templates. Thanks.
try this way
(self.tabBarController?.viewControllers?[0] as! FirstViewController).totTime = totalTime
(self.tabBarController?.viewControllers?[0] as! FirstViewController).timeInt = intTime
self.tabBarController?.selectedIndex = 0
self.tabBarController?.tabBar.isHidden = false try this
A much better way to pass data by using protocols, you can define a protocol like below
protocol PassDataDelegate{
func updateFirstVc(totalTime:String)
}
and in your SecondViewController class have a delegate property like below
class SecondViewController:UIViewController{
myDelegate:PassDataDelegate?//declaration part
#IBAction func updateBut(_ sender: Any) {
myDelegate.updateFirstVc(totalTime:totalTime)
}
}
And finally in your UITabController class implement the protocol
class myTabController:UITabController,PassDataDelegate{
var firstController:FirstViewController? //declaration part
var secondController:SecondViewController?
override func viewDidLoad(){
super.viewDidLoad()
//initialize your view controller here
self.firstViewController = FirstViewController()
self.secondViewController = SecondViewController()
self.secondViewController.myDelegate = self //assign delegate to second vc
self.viewcontrollers = [firstController, secondController]
}
updateFirstVc(totalTime:totalTime){
self.firstViewController?.totTime = totalTime
self.selectedIndex = 0// here change the tab to first vc if you want to switch the tab after passing data
}
}
I am new to iOS correct me If I am wrong,
The reason why the TabBar is not visible since you are instantiating new FirstViewController which is present on top of your TabBar.
TabBar by default does this Job or Add the new viewController to the TabBar Stack.
tabBarController.viewControllers.append(myVC)
For passing the data TabBar holds the reference of all its ViewControllers. So you can set or get in each other ViewControllers like this
var yourData{
set{
let yourVC = self.tabBarController?.viewController[0] as? FirstViewController ?? ErrorClass
yourVC.dataObj = newValue
}
get{
let yourVC = self.tabBarController?.viewController[0] as? FirstViewController ?? ErrorClass
return yourVC.dataObj
}
I have a FirstVC with table view with segue to another SecondVC where i pass the name of pressed cell. In SecondVC i have another tableview which i want to populate with data. I have a function called gettingUrls() which is pulling data for my table view:
DataService.instance.mainRef.child("Folders").child("\(folderName)").observeSingleEvent(of: .value) { (snapshot: DataSnapshot) in...}
where "folderName" is the value from FirstVC. This function is implemented into "pull to refresh feature" and it works great. However when i try to run the function itself in viewDidLoad it keeps crashing the app because of empty folderName value. I just can't understand why at this point the value from segue is available in refresh function and not in viewDidLoad.
Here is the code of segue:
let detailVC = self.storyboard?.instantiateViewController(withIdentifier: "DetailVC") as! DetailVC
self.navigationController?.pushViewController(detailVC, animated: true)
self.present(detailVC, animated: true, completion: nil)
detailVC.folderName = fileName
How can i run the function in viewDidLoad?
You're presenting the DetailVC's view before you've set its folderName property. The view has loaded but it doesn't yet have a folderName so the program crashes. You should place the line detailVC.folderName = fileName before you present the DetailVC.
You also don't need both the 2nd and 3rd lines - either present the new view controller or push it onto the navigation stack, not both.
You should write code with segues to push viewControllers like following not with navigationController
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "Verification") {
let vc = segue.destination as! MyViewController
vc.delegate = self
vc.property = value
}
}
So with #haarismuneer help, it was enough to pass the variable before initializing SecondVC:
detailVC.folderName = fileName
self.navigationController?.pushViewController(detailVC, animated: true)
Suppose I have three view controllers in a Main.storyboard. Two of the three, vc_login and vc_studyDesc load the other view controller using a UIButton with 'present modally' option.
The other one vc_signup has a UIButton, which may go back to the previous controller. To implement this, I used the following methods:
vc_studyDesc has an identifier of studyDesc; I let it pass its identifier to vc_signup. In the same way, vc_login has login as an identifier.
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if sender as! UIButton == qnaSignUp {
let signup = segue.destinationViewController as! vc_signup
signup.latestVC = "studyDesc"}}
This one is in the UIViewController class for vc_signup. By referencing a string latestVC, the method determines which VC to move on.
#IBAction func backBtnClick(sender: UIButton) {
print("latestVS: \(latestVC)")
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier(latestVC)
vc.modalTransitionStyle = UIModalTransitionStyle.CrossDissolve
print("check check")
self.presentViewController(vc, animated: true, completion: nil)}
The problem I have is that the app gets terminated when vc_studyDesc is called by vc_signup. I found that this is because I missed a significant variable which must be loaded in vc_signup.
vc_studyDesc has some data to be referenced from Firebase when it is loaded. I did this by loading a variable postID from the prior vc to vc_studyDesc; which is vc_list.
So I just saved postID using NSUserdefaults.standardUserDefaults(). It is solved but I'm wondering if there's any way to pass data using the way I used in vc_signup.
As far as I see, I cannot find any way to pass the data into vc_studyDesc.swift; for the vc is chosen by its identifier..
Can I pass the variable I want in the way I want?? And adding tags would be appreciated!
So there are a couple problems with this design.
When you instantiate a viewController you are creating a new instance of that class, and presenting it adds it to the stack. Think of the stack like a deck of cards, you start with one card and then add or remove them, the top card being the visible vc. When you are going back to studyDesc you are instantiating and presenting it so you will have 3 VCs in your stack, of which two are studyDesc (the one you started with and the one you add when you try to go back)
To remove a VC from the stack you can use
dismissViewController(animated: true, completion: nil)
or if you have the VCs in a navigation controller you can use
popViewControllerController(animated: true, completion: nil)
in terms of passing information between viewControllers, if the info is in the VC you use to present your new controller you can use prepareForSegue like you already have. To pass information back you should use a delegate pattern. So to implement a delegate pattern in this case you would do the following:
Declare a protocol (not inside your classes, above there but below your import's)
protocol SignUpDelegate {
signInCompleted(infoToPass: AnyObject)
}
Then have your studyDesc class conform to this protocol and implement the function signInCompleted
StudyDescVC: UIViewController, SignUpDelegate {
func signInCompleted(infoToPass: AnyObject) {
// do what you want with the info here
}
}
Then in your signUpVc add a var delegate (which will be used to call the signInCompeleted function)
class SignInVC: UIViewController {
var delegate: SignUpDelegate!
func finishedSigningIn() {
delegate.signInCompleted(infoToPass: //yourinfo)
self.dismissViewControllerAnimated(true, completion: nil)
}
And then in your prepareForSegue set the delegate
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if sender as! UIButton == qnaSignUp {
let signup = segue.destinationViewController as! vc_signup
signup.delegate = self
}
}
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier(latestVC) as! YOUR_VIEW_CONTROLLER_NAME
vc.modalTransitionStyle = UIModalTransitionStyle.CrossDissolve
vc.name = "Andrew"
print("check check")
self.presentViewController(vc, animated: true, completion: nil)
//set a variale or property to your viewController
class YOUR_VIEW_CONTROLLER_NAME: UIViewController {
var name: String?
}
I have three View Controllers embedded in Navigation Controller. I want to go from VC1 to VC3 so that in VC3 the Navigation Item's back button would direct the user to VC2 instead of VC1. I think this should be done either by adding the VC2 to the Navigation Stack between VC1 and VC3 when VC3 is created or by skipping the second View Controller.
I tried this:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let identifier = segue.identifier {
switch identifier {
case "JumpToThirdVCSegue":
if let secondvc = segue.destinationViewController as? SecondViewController {
secondvc.performSegueWithIdentifier("ThirdVCSegue", sender: self)
}
default: break
}
}
}
but I couldn't get it working. Perhaps performing a segue isn't possible when the View Controller isn't open yet?
What is the best way to skip a View Controller / add a View Controller in the middle of Navigation Stack? I hope this helps you to understand what I'm trying to do:
Something like this should work:
self.navigationController?.pushViewController(viewController2, animated: true)
self.navigationController?.pushViewController(viewController3, animated: true)
EDIT:
If you want to push the second view controller without being noticed by the user you need to add it to the navigation controller after the third view controller is pushed. This can be done by implementing UINavigationControllerDelegate. You can store your second view controller in a variable and insert it to the navigation controllers hierarchy in delegate method. Your main view controller will look like following:
class MyViewController: UIViewController, UINavigationControllerDelegate {
var viewControllerToInsertBelow : UIViewController?
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.delegate = self
}
func pushTwoViewControllers() {
if let viewController2 = self.storyboard?.instantiateViewControllerWithIdentifier("id1"),
let viewController3 = self.storyboard?.instantiateViewControllerWithIdentifier("id2") { //change this to your identifiers
self.viewControllerToInsertBelow = viewController2
self.navigationController?.pushViewController(viewController3, animated: true)
}
}
//MARK: - UINavigationControllerDelegate
func navigationController(navigationController: UINavigationController, didShowViewController viewController: UIViewController, animated: Bool) {
if let vc = viewControllerToInsertBelow {
viewControllerToInsertBelow = nil
let index = navigationController.viewControllers.indexOf(viewController)!
navigationController.viewControllers.insert(vc, atIndex: index)
}
}
}
if var navstack = navigationController?.viewControllers{
navstack.append(contentsOf: [vc1,vc2])
navigationController?.setViewControllers(navstack, animated: true)
}
Works well
Edit: using swift and segues, this should work:
override func performSegueWithIdentifier(identifier: String?, sender: AnyObject?) {
super.performSegueWithIdentifier(identifier, sender: sender);
if identifier == "JumpToThirdVCSegue" {
// now the vc3 was already pushed on the navigationStack
var navStackArray : [AnyObject]! = self.navigationController!.viewControllers
// insert vc2 at second last position
navStackArray.insert(viewController2, atIndex: navStackArray.count - 2)
// update navigationController viewControllers
self.navigationController!.setViewControllers(navStackArray, animated:false)
}
}
So you override the performSegueWithIdentifier in the VC1 in order to change the navigation stack when the segue to VC3 has actually been performed (and is not only in preparation).
This assumes, that you want to handle this special navigation logic in VC1.
You can use method
func setViewControllers(_ viewControllers: [UIViewController],
animated: Bool)
Here's the documentation (link) that solves the UIViewController skipping problem.
Simply pass all the needed UIViewControllers to it (in navigational order) and the last one will be made as the current active UIViewController (if it already isn't the active one).
My solution would be to keep a BOOL property of when you should skip to third and when not skip, like declaring ’shouldSkip’ in VC2 so that if u set it in prepare segue like below you can act according to that in VC2
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let identifier = segue.identifier {
switch identifier {
case "JumpToThirdVCSegue":
secondvc.shouldSkip=true
}
default: break
}
}
}
and then in viewDidload VC2 you should check this BOOL and if it is true and perform segue and if not just move on
you could also pass pass whenever that kind of skip is not necessary
Building off of MarkHim's answer, I was getting a Black screen when navigating back to the inserted view controller so I came up with the following solution.
BTW - I wanted to insert the new view controller directly under the view controller I just segued to hence the navStack.count - 1 instead of navStack - 2.
Here is my solution:
override func performSegue(withIdentifier identifier: String, sender: Any?) {
super.performSegue(withIdentifier: identifier, sender: sender)
if identifier == "JumpToThirdViewControllerSegue",
let navController = navigationController { // unwrap optional
// initialize the view controller you want to insert
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let viewControllerToInsert = storyboard.instantiateViewController(
withIdentifier: "SecondVC") as! SecondViewController
// set any passed properties
viewControllerToInsert.passedProperty = propertyToPass
// create an object using the current navigation stack
var navStackArray: [UIViewController]! = navController.viewControllers
// insert the newly initialized view controller into the navStackArray
navStackArray.insert(viewControllerToInsert, at: navStackArray.count - 1)
// replace the current navigation stack with the one you just
// inserted your view controller in to
navController.setViewControllers(navStackArray, animated: false)
}
}