Swift - Delegate through Nav Controller - ios

Question

I'm going to include my full code in this but I will try to give pointers to where the relevant bits are. Basically I am returning to a view controller from an Unwind Segue with some new data. I am using that data successfully in the 'NBARotoHome' VC but I additionally need to pass some of that data through an embedded Nav controller to 'NBARotoTabPager' vc.
I am trying to do this using the 'UpdateChildView' delegate (at the top of the first block of code) and calling its method in 'loadViewData() (in the 'if statement' near the bottom of the first block).
protocol UpdateChildView : class {
func updateView()
func test()
var playerSelected: Player? { get set }
}
class RotoViewRoundCell: UITableViewCell{
#IBOutlet weak var categoryLabel: UILabel!
}
class RotoViewRoundHeader: UITableViewCell{
}
class NBARotoHome: UIViewController{
#IBOutlet weak var posPaidLabel: UILabel!
#IBOutlet weak var progressIndicator: UIProgressView!
#IBOutlet weak var vsLabel: UILabel!
#IBOutlet weak var fantasyFundsAmountLabel: UILabel!
#IBOutlet weak var fantasyFundsLabel: UILabel!
#IBOutlet weak var playerName: UILabel!
#IBOutlet weak var roundIndicator: UILabel!
var selectedPlayer: Player!
var firstNavController: UINavigationController!
weak var updateChildView : UpdateChildView?
override func viewDidLoad() {
super.viewDidLoad()
loadViewData()
firstNavController = self.navigationController
let rightBarButton = UIBarButtonItem(title: "Select", style: UIBarButtonItemStyle.plain, target: self, action: #selector(myRightSideBarButtonItemTapped(_:)))
self.navigationItem.rightBarButtonItem = rightBarButton
self.title = "NBA Roto"
}
func myRightSideBarButtonItemTapped(_ sender:UIBarButtonItem!){
performSegue(withIdentifier: "ShowDraft", sender: nil)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ShowDraft" {
let navVC = segue.destination as? UINavigationController
let nbaDraftList = navVC?.viewControllers.first as! NBADraftList
nbaDraftList.mainNavController = firstNavController
}
if (segue.identifier == "buyNavControllerChild"){
// let navVC = segue.destination as? UINavigationController
// let buyVC = navVC?.viewControllers.first as! NBARotoTabPager
// buyVC.delegate = self
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
}
#IBAction func prepareForUnwind(segue: UIStoryboardSegue) {
}
func loadViewData(){
if((selectedPlayer) != nil){
roundIndicator.text = "Upcoming: " + selectedPlayer.game_time
playerName.text = selectedPlayer.Name
vsLabel.text = selectedPlayer.visiting + " # " + selectedPlayer.home
fantasyFundsLabel.text = ""
fantasyFundsAmountLabel.text = ""
updateChildView?.test()
// updateChildView?.playerSelected = selectedPlayer
// updateChildView?.updateView()
}else{
roundIndicator.text = "Select a Player"
playerName.text = "No Player Selected"
vsLabel.text = "--"
fantasyFundsLabel.text = "Fantasy Funds"
fantasyFundsAmountLabel.text = "$10,000"
}
}
}
Because I haven't been able to get the delegate to work, I have been playing around with setting its delegate property in the above 'prepare' method -'buyVC.delegate = self' - but I'm getting 'buyVC has no member delegate' so that has been a dead end.
The next bit of code is the NBARotoTabPager vc which is embedded in the navigation controller. For reasons I'm no longer sure about I decided to make it a subclass of NBARotoHome, but its basically a custom tab pager that uses a segmented control to switch between two additional vcs.
The most important step at this point is just getting the 'test' function to work (which just prints 'test'. Its implemented in the below block of code second from the bottom above updateView).
class NBARotoTabPager: NBARotoHome, UpdateChildView{
#IBOutlet weak var segmentedControl: UISegmentedControl!
#IBOutlet weak var scoreKey: UIBarButtonItem!
#IBOutlet weak var standings: UIBarButtonItem!
var playerSelected: Player?
override func viewDidLoad() {
navigationController?.navigationBar.barTintColor = UIColor(red: 27/255, green: 27/255, blue: 27/255, alpha: 1)
scoreKey.setTitleTextAttributes([NSFontAttributeName: UIFont(name: "Helvetica", size: 13.0)!], for: UIControlState.normal)
scoreKey.tintColor = UIColor.blue
standings.setTitleTextAttributes([NSFontAttributeName: UIFont(name: "Helvetica", size: 13.0)!], for: UIControlState.normal)
standings.tintColor = UIColor.blue
setupView()
}
private func setupView() {
setupSegmentedControl()
updateView()
}
private func setupSegmentedControl() {
// Configure Segmented Control
segmentedControl.removeAllSegments()
segmentedControl.insertSegment(withTitle: "Live", at: 0, animated: false)
segmentedControl.insertSegment(withTitle: "Avg / +", at: 1, animated: false)
segmentedControl.addTarget(self, action: #selector(selectionDidChange(_:)), for: .valueChanged)
segmentedControl.selectedSegmentIndex = 0
}
func selectionDidChange(_ sender: UISegmentedControl) {
updateView()
}
private lazy var viewLiveTab: NBARotoLive = {
// Load Storyboard
let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
// Instantiate View Controller
var viewController = storyboard.instantiateViewController(withIdentifier: "NBARotoLive") as! NBARotoLive
if((self.playerSelected) != nil){
viewController.selectedPlayer = self.playerSelected
}
// Add View Controller as Child View Controller
self.add(asChildViewController: viewController)
return viewController
}()
private lazy var viewAvgsTab: NBARotoAvgs = {
// Load Storyboard
let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
// Instantiate View Controller
var viewController = storyboard.instantiateViewController(withIdentifier: "NBARotoAvgs") as! NBARotoAvgs
if((self.playerSelected) != nil){
viewController.selectedPlayer = self.playerSelected
}
// Add View Controller as Child View Controller
self.add(asChildViewController: viewController)
return viewController
}()
private func add(asChildViewController viewController: UIViewController) {
// Add Child View Controller
addChildViewController(viewController)
// Add Child View as Subview
view.addSubview(viewController.view)
// Configure Child View
viewController.view.frame = view.bounds
viewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
// Notify Child View Controller
viewController.didMove(toParentViewController: self)
}
private func remove(asChildViewController viewController: UIViewController) {
// Notify Child View Controller
viewController.willMove(toParentViewController: nil)
// Remove Child View From Superview
viewController.view.removeFromSuperview()
// Notify Child View Controller
viewController.removeFromParentViewController()
}
internal func test(){
print("test")
}
internal func updateView() {
if segmentedControl.selectedSegmentIndex == 0 {
let position = viewAvgsTab.tableView.contentOffset.y;
viewLiveTab.tableView.contentOffset = CGPoint(x:0, y:position);
remove(asChildViewController: viewAvgsTab)
add(asChildViewController: viewLiveTab)
} else {
let position = viewLiveTab.tableView.contentOffset.y;
viewAvgsTab.tableView.contentOffset = CGPoint(x:0, y:position);
remove(asChildViewController: viewLiveTab)
add(asChildViewController: viewAvgsTab)
}
}
}
I've looked at a lot of examples but I don't understand the whole 'setting the delegate' thing i.e. theSecondViewController.delegate = self. Sometimes I see examples where you don't need to do this. And other times it seems like my VCs don't even have a delegate property. So I'm not sure if that's my specific problem or not but any direction would be greatly appreciated. Thanks

Answer 1

There are three steps to implement a delegate.
create a protocol.. (you've already done this by creating a updateChildView protocol)
you need to implement this protocol in the class you wish to receive and process this data.. (you've not done this step and thats why you cant set buyVC.delegate = self)
you need to add a property in ViewController2 called "delegate" and make it as a type of your protocol in step 1 (you've not done this step and there is no property called "delegate" in vc2 .. that's why you get this error 'buyVC has no member delegate')
Here's a quick example:
Protocol:
protocol UpdateChildView{ //removed :class
func updateView()
func test()
var playerSelected: Player? { get set }
}
Viewcontroller A:
class NBARotoHome: UIViewController, UpdateChildView { //added conformance to the protocol
//add the methods for conforming to protocol and add your implementation
func updateView() {
//add your implementation
}
func test(){
//add your implementation
}
var playerSelected: Player? {
//add your implementation
}
prepare(for: Segue) {
/** code for passing data **/
let navVC = segue.destination as? UINavigationController
let buyVC = navVC?.viewControllers.first as! NBARotoTabPager
buyVC.delegate = self
//sets the delegate in the new viewcontroller
//remember.. delegate is a property in the next vc
// and the property only accepts any viewcontroller that is implements updatechildview protocol
present(vc2)
}
}
viewcontroller2 :
class viewControllerB: UIViewController {
var delegate: UpdateChildView? //add this
viewdidload {
delegate?.test() //call the func in the previous vc
}
}