The delegate in this app is not being set - ios

Question

I have an app with two view controllers... ViewController and CollectionViewController. I have filter functions in the viewController that perform color filters on an image loaded into this view controller. The CollectionViewController contains a collection view that acts as a horizontal scrolling menu with cells, that when pressed, are supposed to call the filter functions in ViewController. The storyboard has a show segue with ID "FilterSegue"
I got it to work with Notification Centers but I wanted to try to get it to work with protocols and delegates to learn about the methods. I received some suggestions, but have been unable to get the delegate to set despite numerous attempts.
Here is the code:
ViewController:
import UIKit
class ViewController: UIViewController, FilterDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "FilterSegue" {
let destvc = segue.destinationViewController as! CollectionViewController
destvc.filterDelegate = self
}
}
func onRedFilter() {
// some code
}
func onGreenFilter() {
// some code
}
func onBlueFilter() {
// some code
}
func onUnfiltered() {
// some code
}
}
CollectionViewController:
import UIKit
//Protocols for filter functions called by the filter menu collection view custom cells.
protocol FilterDelegate: class {
func onRedFilter()
func onGreenFilter()
func onBlueFilter()
func onUnfiltered()
}
class CollectionViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UICollectionViewDelegate {
let reuseIdentifier = "FilterCell"
var filterDelegate: FilterDelegate? = nil
#IBOutlet var collectionView: UICollectionView!
// Filter labels for custom filter menu cells.
var tableData:[String] = ["Red Filter",
"Green Filter",
"Blue Filter",
"Unfilter",
"New Filter 1",
"New Filter 2"]
// Filter images for custom filter menu cells.
var tableImages: [String] = ["waterfallred.png",
"waterfallgreen.png",
"waterfallblue.png",
"waterfall.png",
"waterfall.png",
"waterfall.png"]
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
// Set up collectionView for the filters.
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.itemSize = CGSize(width: 120, height: 80)
collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
collectionView!.registerClass(colvwCell.self, forCellWithReuseIdentifier: reuseIdentifier)
collectionView!.backgroundColor = UIColor.whiteColor()
self.view.addSubview(collectionView!)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
// Set uo required methods for collection view.
func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return tableData.count
}
// Method for custom collection view cell texts and images.
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell: colvwCell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath) as! colvwCell
cell.backgroundColor = UIColor.grayColor()
cell.lblCell.text = tableData[indexPath.row]
cell.imgCell.image = UIImage(named: tableImages[indexPath.row])
return cell
}
// Method for calling functions upon pressing custom filter menu collection view cells. In this case, the filter functions in the main view controller are called using notifications.
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
print("Cell \(indexPath.row) selected")
guard let filterDelegate = filterDelegate else {
print("Filter delegate wasn't set!")
return
}
switch indexPath.row {
case 0:
filterDelegate.onRedFilter()
case 1:
filterDelegate.onGreenFilter()
case 2:
filterDelegate.onBlueFilter()
case 3:
filterDelegate.onUnfiltered()
default:
print("No available filter.")
}
}
}
The guard statement returns "Filter delegate wasn't set!" on any depressed cell on the collection view menu.

Answer 1

instead of this
protocol FilterDelegate: class {
func onRedFilter()
----
}
try this
protocol FilterDelegate {
func onRedFilter()
----
}

Answer 2

I found the answer...
I realized that the segue wasn't being set because it was trying to instantiate another collection view controller with the segue. I removed the prepareForSegue altogether and the segue from the storyboard.
I have a button called onFilter2 on the main view controller that instantiates the collection view in a container on a press (calls a function showFilterMenu to show the filter menu) and then hides it on a second press (hideFilterMenu). The showFilterMenu function is where the colectionviewcontroller is instantiated. So, I set the delegate in this function. It took one line of code.
Here is the function executed upon pressing the filter button with the correct call of the delegate.
// New onFilter button action that shows/hides the filter collection view scroll bar on main view controller.
#IBAction func onFilter2(sender: UIButton) {
if filterButtonOn == true {
if (sender.selected) {
hideFilterMenu()
editButton.selected = false
sender.selected = false
} else {
showFilterMenu()
sender.selected = true
hideSliderMenu()
editButton.selected = false
//Reset color sliders to initial values.
redHorizontalSlider?.setValue(0, animated: false)
greenHorizontalSlider?.setValue(0.0, animated: false)
blueHorizontalSlider?.setValue(0.0, animated: false)
// Set initial values for color indicators.
redSliderIndicator.text = "0.00"
greenSliderIndicator.text = "0.00"
blueSliderIndicator.text = "0.00"
}
}
}
// Shows the filter menu scrolling bar in container view upon request.
func showFilterMenu() {
let newViewController = self.storyboard?.instantiateViewControllerWithIdentifier("FilterCollectionView") as! CollectionViewController
newViewController.view.translatesAutoresizingMaskIntoConstraints = false
self.toggleOnViewController(newViewController)
self.currentViewController = newViewController
// Set the delegate for the filter functions called by the cells in the collectionViewController filter menu.
// Set the delegate for the filter functions called by the cells in the collectionViewController filter menu.
//Here is the line of code that fixes the problem...
newViewController.filterDelegate = self
filterMenuShowOn = true
}
// Hides filter menu scrolling bar from container view upon request.
func hideFilterMenu() {
currentViewController!.view.alpha = 1
UIView.animateWithDuration(0.5, animations: {
self.currentViewController!.view.alpha = 0
},
completion: { finished in
self.currentViewController!.view.removeFromSuperview()
self.currentViewController!.removeFromParentViewController()
})
}
I want to thank Matt for getting me thinking about what was happening.