I have a RootVC with container views for MapVC and ListVC.
Since I need to make an API call and share the results amongst both MapVC and ListVC, I created a RootVCDelegate.
protocol RootVCDelegate {
func fetch(results: [Object]) -> Void
}
in prepare(for UIStoryboardSegue:) I respectively set RootVCDelegate property to MapVC or ListVC depending on the identifier. I know this won't work, because delegate property can only have one value.
Delegation pattern won't work here, so how can I share results of async call between these view controllers?
you can make RootVCDelegate an array of delegates and then when you want to perform on the delegates do delegats.forEach { ..... } and when assigning a delegate just append the delegate to delegates
Example:
// Delegate Protocol
protocol RootVCDelegate {
fetch(results: [Objects]) //returning Void does nothing so no need to write it
}
// RootVC
class RootVC {
delegates: [RootVCDelegate]
prepare(for segue: UIStoryboardSegue) {
let destination = (segue.destination as? UINavigationController).rootViewController ?? segue.destination // how I like to handle things if there's a possibility of a UINavigationController housing my UIViewController
switch destination {
case _ as MapVC: delegates.append(destination)
case _ as ListVC: delegates.append(destination)
default: return
}
}
}
This may be what you're asking for?
Related
I have a view controller, lets call it vc1, which passes some data to another (vc2) using prepare for segue, and then calling performSegue.
Is there a way to pass some data back from vc2 to vc1 when vc2 is dismissed by swiping down?
Thanks,
Edit --
Apologies for the lack of information, very new to swift so unsure of the correct question to ask in this situation.
To elaborate, the root of the issue at the moment is that vc2 is not dismissed programatically. ie there is currently no function called, it is simply dismissed by the user swiping down.
Is there some function that I can include to capture this dismissal, and use it to send data back to vc1?
I would prefer not to add any buttons to vc2 if possible.
Apologies again, and I appreciate all the help given already!
Try This
class VCOne: UIViewController {
//Create a shared instance of VCOne
static var sharedInstance:VCOne?
//Let the data to be passed back to VCOne is of type string
var dataToBePassedBack:String?
override func viewDidLoad() {
super.viewDidLoad()
//set the sharedInstance to self
VCOne.sharedInstance = self
}
}
Class VCTwo:UIViewController{
//function in which you are dismissing your current VC you can use the shared
instance to pass the data back
func dismissVC(){
//before dismissing the VCTwo you can set the value for VCOne
VCOne.sharedInstance?.dataToBePassedBack = "data"
}
}
Using Protocol And Delegate You Do or Other Option is NSotificationcenter.
One way yo do it is to create another file that it the controller of everything and then have a delegate that always notifies the view controllers when new changes are available. I will walk it through.
protocol HeadControllerDelegate {
// Create a function that sends out the data to the delegates when it is called
// You can use your custom struct here to pass more data easly
func didReciveNewData(myData: String?)
}
struct HeadController {
// Create a shared instance so that the viewcontroller that conforms to the view as well as when we sends out the data the delegate is correct
static var shared = HeadController()
// Creates the delegate, every view can asign it to
public var delegate: HeadControllerDelegate?
// Add all your values here you want to pass back
var myValue: String? {
// The didSet gets called every time this value is set, and then is it time to call the delegate method
didSet {
// Calls the delegates didReciveMethod to notify the delegates that new data exsists
delegate?.didReciveNewData(myData: myValue)
}
}
}
Now in your viewcontroller class where you would like the data to be avaiable (as you said when you swipe down)
class ViewController: UIViewController {
// Here you create a property of the shared instance
let headController = HeadController.shared
override func viewDidLoad() {
super.viewDidLoad()
// Set yourself as the delegate for the headController delegate to recive data
headController.delegate = self
}
}
extension ViewController: HeadControllerDelegate {
// here will the data be recived
func didReciveNewData(myData: String?) {
// handle the data here, you have now got newData
print(myData)
}
}
In the class where you want to pass data you just do it like this. The beauty of this is that you can have multiple classes or structs that writes to the head controllers data (just make sure you do it thought the shared instance). It is also a good pracice according to we to use the delegate pattern.
class Sender {
var headController = HeadController.shared
func sendData(data: String) {
// Here you change the data of the headcontroller wich will send the data to all the delegates
headController.myValue = data
}
}
Hope this answer helps. If you have any questions please let me know.
UPDATE -- EASIER SOLUTION
Here is an easier solution but is less scalable as the previous one according to me.
In prepareForSegue simply pass over your current viewContorller as a field in the destination view controller. Then when viewDidDissapear in the new view controller you can simply pass back the data. Not to worry, I will show you!
In prepare for Segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let dc = segue.destination as? SecondViewController {
dc.viewController = self
}
}
And declare the secondViewContorller as following. The ViewDidDisappear method will be called when the view has dismissed, and therefore can you pass over the data to the view controller you have set before using the prepare for segue method.
class SecondViewController: UIViewController {
var viewController: UIViewController?
override func viewDidLoad() {
super.viewDidLoad()
}
override func viewDidDisappear(_ animated: Bool) {
(viewController as? ViewController)?.value = 2
}
}
Then you could update the UI using a didSet, which simply will be called when the property is set, which will be done in the view did disappear method.
var value: Int = 0 {
didSet {
print(value)
text?.text = "\(value)"
}
}
Hope this helps!
I m confuse about call back using protocol and delegate.
The problem is. I have two viewcontrollers vcA & vcB
and vcA have a tableView, vcB have a button.
vcA click the cell to vcB.
Then I want to click the button in vcB and do the following two things.
1.vcA tableView reloadData.
2.vcB popViewcontroller To vcA.
I can't understand how to solve this issue.
Have any sample to teach me?
Thanks.
This is the delegate solution , but it's better to put the self.tableView.reloadData() method inside viewDidAppear , as it's being called when you pop VcB
class VcA: UIViewController ,TableRefresh {
func reloadTable()
{
// reload here
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let des = segue.destination as! VcB
des.delegate = self
}
}
protocol TableRefresh {
func reloadTable()
}
class VcB: UIViewController {
var delegate: TableRefresh?
#IBAction func closeClicked(_ sender: UIButton) {
self.delegate?.reloadTable()
// pop here
}
}
I hope this could work for you:
class vcA : UIViewController {
override func viewWillAppear(_ animated: Bool) {
tableView.reloadData()
}
}
class vcB : UIViewController {
#IBAction fun button(bin : UIButton){
self.navigationController.popViewController(true)
}
}
It's not possible to call the methods of any VC objects if it's not in your memory.
For the first time, it vcB will not be in memory. Hence the object of the same is not in existence.
If you really want to call a function of that class and if its feasible crate an object of vcB and call the method.
or you might try a shared object of the VC and keep on using the same if it's feasible. you may post exact scenario so that people can suggest something better
Your vcA has a reference to the vcB, so you are able to write something like this in the vcA
class vcA {
var vcB: vcB?
...
vcB?.doSmth()
....
}
but there is no way for you to call vcA from the vcB since it doesn't have a reference to it. So to let vcA know that something happened in vcB or to call some function from vcB you can do several things.
Delegates, Key-Value Observing, Reactive Programming and some others.
Since you asked for the delegates solution lets stick to it.
The general idea behind delegates is as the name says to delegate someone else to do something. In your case, you want to delegate button click handling to the vcA. To do so, you will need a couple of things.
Next steps are just the implementation of the idea described above.
class VcA {
var vcB: VcB?
...
vcB?.delegate = self
...
vcB?.doSmth()
....
}
extension VcA: VcBDelegate {
func buttonIsClicked() {
// reload data
// pop vcB
}
}
protocol VcBDelegate: class {
func buttonIsClicked()
}
class VcB {
var delegate: VcBDelegate?
...
// when the button is clicked
// delegate handling to someone who is 'listening' for this event
self.delegate?.buttonIsClicked()
...
}
Notice how delegate in VcB is optional, meaning that if no one is signed as a delegate for VcB, the event will simply be ignored.
There are multiple ways to do this.
1: Put tableView.reloadData() in viewDidAppear() and then just pop vcB
2: When you are pushing vcB you create a reference to it and then in vcB you have a listener that you apply to the reference. like so:
class viewControllerB: UIViewController {
var reloadTableView: (() -> ())
#objc func buttonPressed() {
reloadTableView()
self.navigationController?.popViewController(animated: true)
}
}
And then:
let vcB = viewControllerB()
vcB.reloadTableView = {
self.tableView.reloadData()
}
present(vcB, animated: true)
3: Do as Sh_Khan
Say I have multiple view controllers in my Swift app and I want to be able to pass data between them. If I'm several levels down in a view controller stack, how do I pass data to another view controller? Or between tabs in a tab bar view controller?
(Note, this question is a "ringer".) It gets asked so much that I decided to write a tutorial on the subject. See my answer below.
Your question is very broad. To suggest there is one simple catch-all solution to every scenario is a little naïve. So, let's go through some of these scenarios.
The most common scenario asked about on Stack Overflow in my experience is the simple passing information from one view controller to the next.
If we're using storyboard, our first view controller can override prepareForSegue, which is exactly what it's there for. A UIStoryboardSegue object is passed in when this method is called, and it contains a reference to our destination view controller. Here, we can set the values we want to pass.
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "MySegueID" {
if let destination = segue.destination as? SecondController {
destination.myInformation = self.myInformation
}
}
}
Alternatively, if we're not using storyboards, then we're loading our view controller from a nib. Our code is slightly simpler then.
func showNextController() {
let destination = SecondController(nibName: "SecondController", bundle: nil)
destination.myInformation = self.myInformation
show(destination, sender: self)
}
In both cases, myInformation is a property on each view controller holding whatever data needs to be passed from one view controller to the next. They obviously don't have to have the same name on each controller.
We might also want to share information between tabs in a UITabBarController.
In this case, it's actually potentially even simpler.
First, let's create a subclass of UITabBarController, and give it properties for whatever information we want to share between the various tabs:
class MyCustomTabController: UITabBarController {
var myInformation: [String: AnyObject]?
}
Now, if we're building our app from the storyboard, we simply change our tab bar controller's class from the default UITabBarController to MyCustomTabController. If we're not using a storyboard, we simply instantiate an instance of this custom class rather than the default UITabBarController class and add our view controller to this.
Now, all of our view controllers within the tab bar controller can access this property as such:
if let tbc = self.tabBarController as? MyCustomTabController {
// do something with tbc.myInformation
}
And by subclassing UINavigationController in the same way, we can take the same approach to share data across an entire navigation stack:
if let nc = self.navigationController as? MyCustomNavController {
// do something with nc.myInformation
}
There are several other scenarios. By no means does this answer cover all of them.
This question comes up all the time.
One suggestion is to create a data container singleton: An object that gets created once and only once in the life of your application, and persists for the life of your app.
This approach is well suited for a situation when you have global app data that needs to be available/modifiable across different classes in your app.
Other approaches like setting up one-way or 2-way links between view controllers are better suited to situations where you are passing information/messages directly between view controllers.
(See nhgrif's answer, below, for other alternatives.)
With a data container singleton, you add a property to your class that stores a reference to your singleton, and then use that property any time you need access.
You can set up your singleton so that it saves it's contents to disk so that your app state persists between launches.
I created a demo project on GitHub demonstrating how you can do this. Here is the link:
SwiftDataContainerSingleton project on GitHub
Here is the README from that project:
SwiftDataContainerSingleton
A demonstration of using a data container singleton to save application state and share it between objects.
The DataContainerSingleton class is the actual singleton.
It uses a static constant sharedDataContainer to save a reference to the singleton.
To access the singleton, use the syntax
DataContainerSingleton.sharedDataContainer
The sample project defines 3 properties in the data container:
var someString: String?
var someOtherString: String?
var someInt: Int?
To load the someInt property from the data container, you'd use code like this:
let theInt = DataContainerSingleton.sharedDataContainer.someInt
To save a value to someInt, you'd use the syntax:
DataContainerSingleton.sharedDataContainer.someInt = 3
The DataContainerSingleton's init method adds an observer for the UIApplicationDidEnterBackgroundNotification. That code looks like this:
goToBackgroundObserver = NSNotificationCenter.defaultCenter().addObserverForName(
UIApplicationDidEnterBackgroundNotification,
object: nil,
queue: nil)
{
(note: NSNotification!) -> Void in
let defaults = NSUserDefaults.standardUserDefaults()
//-----------------------------------------------------------------------------
//This code saves the singleton's properties to NSUserDefaults.
//edit this code to save your custom properties
defaults.setObject( self.someString, forKey: DefaultsKeys.someString)
defaults.setObject( self.someOtherString, forKey: DefaultsKeys.someOtherString)
defaults.setObject( self.someInt, forKey: DefaultsKeys.someInt)
//-----------------------------------------------------------------------------
//Tell NSUserDefaults to save to disk now.
defaults.synchronize()
}
In the observer code it saves the data container's properties to NSUserDefaults. You can also use NSCoding, Core Data, or various other methods for saving state data.
The DataContainerSingleton's init method also tries to load saved values for it's properties.
That portion of the init method looks like this:
let defaults = NSUserDefaults.standardUserDefaults()
//-----------------------------------------------------------------------------
//This code reads the singleton's properties from NSUserDefaults.
//edit this code to load your custom properties
someString = defaults.objectForKey(DefaultsKeys.someString) as! String?
someOtherString = defaults.objectForKey(DefaultsKeys.someOtherString) as! String?
someInt = defaults.objectForKey(DefaultsKeys.someInt) as! Int?
//-----------------------------------------------------------------------------
The keys for loading and saving values into NSUserDefaults are stored as string constants that are part of a struct DefaultsKeys, defined like this:
struct DefaultsKeys
{
static let someString = "someString"
static let someOtherString = "someOtherString"
static let someInt = "someInt"
}
You reference one of these constants like this:
DefaultsKeys.someInt
Using the data container singleton:
This sample application makes trival use of the data container singleton.
There are two view controllers. The first is a custom subclass of UIViewController ViewController, and the second one is a custom subclass of UIViewController SecondVC.
Both view controllers have a text field on them, and both load a value from the data container singlelton's someInt property into the text field in their viewWillAppear method, and both save the current value from the text field back into the `someInt' of the data container.
The code to load the value into the text field is in the viewWillAppear: method:
override func viewWillAppear(animated: Bool)
{
//Load the value "someInt" from our shared ata container singleton
let value = DataContainerSingleton.sharedDataContainer.someInt ?? 0
//Install the value into the text field.
textField.text = "\(value)"
}
The code to save the user-edited value back to the data container is in the view controllers' textFieldShouldEndEditing methods:
func textFieldShouldEndEditing(textField: UITextField) -> Bool
{
//Save the changed value back to our data container singleton
DataContainerSingleton.sharedDataContainer.someInt = textField.text!.toInt()
return true
}
You should load values into your user interface in viewWillAppear rather than viewDidLoad so that your UI updates each time the view controller is displayed.
Another alternative is to use the notification center (NSNotificationCenter) and post notifications. That is a very loose coupling. The sender of a notification doesn't need to know or care who's listening. It just posts a notification and forgets about it.
Notifications are good for one-to-many message passing, since there can be an arbitrary number of observers listening for a given message.
Swift 4
There are so many approaches for data passing in swift. Here I am adding some of the best approaches of it.
1) Using StoryBoard Segue
Storyboard segues are very much useful for passing data in between Source and Destination View Controllers and vice versa also.
// If you want to pass data from ViewControllerB to ViewControllerA while user tap on back button of ViewControllerB.
#IBAction func unWindSeague (_ sender : UIStoryboardSegue) {
if sender.source is ViewControllerB {
if let _ = sender.source as? ViewControllerB {
self.textLabel.text = "Came from B = B->A , B exited"
}
}
}
// If you want to send data from ViewControllerA to ViewControllerB
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.destination is ViewControllerB {
if let vc = segue.destination as? ViewControllerB {
vc.dataStr = "Comming from A View Controller"
}
}
}
2) Using Delegate Methods
ViewControllerD
//Make the Delegate protocol in Child View Controller (Make the protocol in Class from You want to Send Data)
protocol SendDataFromDelegate {
func sendData(data : String)
}
import UIKit
class ViewControllerD: UIViewController {
#IBOutlet weak var textLabelD: UILabel!
var delegate : SendDataFromDelegate? //Create Delegate Variable for Registering it to pass the data
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
textLabelD.text = "Child View Controller"
}
#IBAction func btnDismissTapped (_ sender : UIButton) {
textLabelD.text = "Data Sent Successfully to View Controller C using Delegate Approach"
self.delegate?.sendData(data:textLabelD.text! )
_ = self.dismiss(animated: true, completion:nil)
}
}
ViewControllerC
import UIKit
class ViewControllerC: UIViewController , SendDataFromDelegate {
#IBOutlet weak var textLabelC: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
#IBAction func btnPushToViewControllerDTapped( _ sender : UIButton) {
if let vcD = self.storyboard?.instantiateViewController(withIdentifier: "ViewControllerD") as? ViewControllerD {
vcD.delegate = self // Registring Delegate (When View Conteoller D gets Dismiss It can call sendData method
// vcD.textLabelD.text = "This is Data Passing by Referenceing View Controller D Text Label." //Data Passing Between View Controllers using Data Passing
self.present(vcD, animated: true, completion: nil)
}
}
//This Method will called when when viewcontrollerD will dismiss. (You can also say it is a implementation of Protocol Method)
func sendData(data: String) {
self.textLabelC.text = data
}
}
Instead of creating a data controller singelton I would suggest to create a data controller instance and pass it around. To support dependency injection I would first create a DataController protocol:
protocol DataController {
var someInt : Int {get set}
var someString : String {get set}
}
Then I would create a SpecificDataController (or whatever name would currently be appropriate) class:
class SpecificDataController : DataController {
var someInt : Int = 5
var someString : String = "Hello data"
}
The ViewController class should then have a field to hold the dataController. Notice that the type of dataController is the protocol DataController. This way it's easy to switch out data controller implementations:
class ViewController : UIViewController {
var dataController : DataController?
...
}
In AppDelegate we can set the viewController's dataController:
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
if let viewController = self.window?.rootViewController as? ViewController {
viewController.dataController = SpecificDataController()
}
return true
}
When we move to a different viewController we can pass the dataController on in:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
...
}
Now when we wish to switch out the data controller for a different task we can do this in the AppDelegate and do not have to change any other code that uses the data controller.
This is of course overkill if we simply want to pass around a single value. In this case it's best to go with nhgrif's answer.
With this approach we can separate view form the logic part.
As #nhgrif pointed out in his excellent answer, there are lots of different ways that VCs (view controllers) and other objects can communicate with each other.
The data singleton I outlined in my first answer is really more about sharing and saving global state than about communicating directly.
nhrif's answer lets you send information directly from the source to the destination VC. As I mentioned in reply, it's also possible to send messages back from the destination to the source.
In fact, you can set up an active one-way or 2-way channel between different view controllers. If the view controllers are linked via a storyboard segue, the time to set up the links is in the prepareFor Segue method.
I have a sample project on Github that uses a parent view controller to host 2 different table views as children. The child view controllers are linked using embed segues, and the parent view controller wires up 2-way links with each view controller in the prepareForSegue method.
You can find that project on github (link). I wrote it in Objective-C, however, and haven't converted it to Swift, so if you're not comfortable in Objective-C it might be a little hard to follow
SWIFT 3:
If you have a storyboard with identified segues use:
func prepare(for segue: UIStoryboardSegue, sender: Any?)
Although if you do everything programmatically including navigation between different UIViewControllers then use the method:
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool)
Note: to use the second way you need to make your UINavigationController, you are pushing UIViewControllers on, a delegate and it needs to conform to the protocol UINavigationControllerDelegate:
class MyNavigationController: UINavigationController, UINavigationControllerDelegate {
override func viewDidLoad() {
self.delegate = self
}
func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
// do what ever you need before going to the next UIViewController or back
//this method will be always called when you are pushing or popping the ViewController
}
}
It depends when you want to get data.
If you want to get data whenever you want, can use a singleton pattern. The pattern class is active during the app runtime. Here is an example of the singleton pattern.
class AppSession: NSObject {
static let shared = SessionManager()
var username = "Duncan"
}
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
print(AppSession.shared.username)
}
}
If you want to get data after any action, can use NotificationCenter.
extension Notification.Name {
static let loggedOut = Notification.Name("loggedOut")
}
#IBAction func logoutAction(_ sender: Any) {
NotificationCenter.default.post(name: .loggedOut, object: nil)
}
NotificationCenter.default.addObserver(forName: .loggedOut, object: nil, queue: OperationQueue.main) { (notify) in
print("User logged out")
}
The way that I would do it would be instead of passing data between view controllers, I would just declare a variable globally. You can even do this with a function!
For example:
var a = "a"
func abc() {
print("abc")
}
class ViewController: UIViewController {
}
I have a button on 2nd viewController, after pressing that button, I would like to dismiss the 2nd viewController and go back to the 1st view controller and immediately call a function that coded inside 1st ViewController swift file.
May I know how can I do that? By segue?
There are many way to do this one of the best way is using protocol and delegate.
You can create one protocol and extend that protocol in your ViewController1. Now create the delegate of protocol in ViewController2 and pass reference of that delegate in the ViewController1's prepareForSegue method.
First create one protocol like this
protocol PassdataDelegate {
func passData()
}
Now extend this protocol in ViewController1 like this and pass the reference of delegate in prepareForSegue method
class ViewController1 : UIViewController, PassdataDelegate {
func passData() {
//Here call your function
self.callMyFunction()
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if (segue.identifier == "SegueIdentifier") {
let destVC = segue.destinationViewController as! ViewController2
destVC.delegate = self
}
}
}
Now create the delegate object of protocolin ViewController2 like this
class ViewController2 : UIViewController {
var delegate: PassdataDelegate?
//Now call the method of this delegate in Button action
#IBAction func buttonClick(sender: UIButton) {
self.delegate.passData()
//Now dismiss the controller
}
}
Note: - Here i am passing stringbut you can pass any type of object that you have declare in your delegate method.
You can refer unwind segue.
class ViewController1 {
#IBAction func doSomeStuffAfterReload(segue: UIStoryboardSegue) {
// do whatever you need to do here.
}
}
On storyboard, from ViewController2 Ctrl+Drag from the button to the exit outlet and select doSomeStuffAfterReload.
You can see it in action here: https://spin.atomicobject.com/2014/10/25/ios-unwind-segues/
Happy coding^^
Hello learning swift and am stuck with calling a method through delegate. Checked multiple answers with similar issues and have tried the solutions but have not been able to successfully apply them to my own situation however I am close.
I have a delegator class named ViewController that holds a variable I would like to change. I have another view called MoodScroll which serves as the delegate. Moodscroll has a button being used to change the value for the variable in ViewController.
ViewController :
class ViewController: UIViewController, AVAudioPlayerDelegate, MoodScrollDelegate {
var alarmSoundType: String?
func acceptData(data: String?) {
alarmSoundType = "\(data)"
print(data)
}
}
MoodScroll :
protocol MoodScrollDelegate {
func acceptData(data: String?)
}
import UIKit
class MoodScroll: UIViewController {
#IBAction func WTF(sender: AnyObject) {
self.delegate?.acceptData("hello")
print("function called")
}
}
The IBAction calls fine as it prints "function called" in the console however it doesn't pass the value to ViewController as alarmSoundType remains nil and also the print command is not called in ViewController as well.
It seems you still have some confusion about delegation : if ViewController conforms to MoodScrollDelegate protocol, then your ViewController object will be the delegate, not the MoodScroll object.
Where do you set the delegate property of your MoodScroll object ?
If this object is created programmatically from your ViewController object, you should set it after initialization :
myMoodScrollObject.delegate = self
Is the object is created using Interface Builder, you can either use an outlet variable for delegate, or set it in prepareForSegue:sender of your ViewController class :
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let scroll = segue.destinationViewController as? MoodScroll{
scroll.delegate = self
}
}
One picky note: the way you have described your problem, it's actually ViewController what you should call the delegate of MoodScroll. Most likely you're probably forgetting to set the delegate property of MoodScroll.
I don't know how these two view controllers relate to each other in your code, but very often you would set the delegate property in the prepareForSegue method of ViewController, for example:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "SegueToMoodScroll" {
let moodScrollController = segue.destinationViewController as! MoodScroll
moodScrollController.delegate = self
}
}