XCode7: "Failed to render instance of" affects all UICollectionViewCells - ios

Question

I currently always get an error when using UICollectionViewCells in a Storyboard. No other Controls show this behavior. How can I get rid of them?
This is how one of the affected CollectionViewCells looks like:
This is how I defined it:
Here is the code of the CategoryCollectionCell
import UIKit
import Foundation
#IBDesignable class CategoryCollectionCell : UICollectionViewCell {
#IBOutlet private weak var imageView: UIImageView!
#IBOutlet private weak var label: UILabel!
internal var id : Int?
override var highlighted : Bool {
didSet {
label.textColor = highlighted ? UIColor.greenColor() : UIColor.whiteColor()
}
}
#IBInspectable var text : String? {
get { return label.text }
set(value) { label.text = value }
}
#IBInspectable var image : UIImage? {
get { return imageView.image }
set(value) { imageView.image = value }
}
}
And this is the code of the CollectionViewController:
extension CategoryViewController : UICollectionViewController {
override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = self.collectionView?.dequeueReusableCellWithReuseIdentifier(kReuseCellIdentifier, forIndexPath: indexPath)
var categoryCollectionCell = cell as? CategoryCollectionCell
if categoryCollectionCell == nil {
categoryCollectionCell = CategoryCollectionCell()
}
let data = getDataForIndexPath(indexPath)
if data != nil {
categoryCollectionCell?.id = data!.id
categoryCollectionCell!.text = data!.category
categoryCollectionCell!.image = data!.image
}
return categoryCollectionCell!
}
override func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 8
}
override func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
return 1
}
}
extension CategoryViewController : UICollectionViewDelegateFlowLayout {
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
guard let flowLayout = collectionViewLayout as? UICollectionViewFlowLayout else {
return CGSize()
}
let width = CGRectGetWidth(collectionView.bounds)
let padding = flowLayout.sectionInset.left + flowLayout.sectionInset.right
let itemSpacing = flowLayout.minimumInteritemSpacing
let size = (width - padding - itemSpacing) / 2
return CGSize(width: size, height: size)
}
}

Answer 1

Ok. I found that the errors displayed by XCode had nothing to do with the actual problem.
The directory /Users/{Username}/Library/Logs/DiagnosticReports should contain files with names like this: IBDesignablesAgentCocoaTouch[...].crash
Inside them I found stacktraces which led me to the real problem:
The problem lied inside the code of a custom UITableViewCell instead of a UICollectionViewCell
class FooTableCell : UITableViewCell {
#IBOutlet private weak var checkmarkImageView: UIImageView!
override internal var selected : Bool {
didSet {
checkmarkImageView.hidden = !selected
}
}
}
The checkmarkImageView was nil when using the designer. Because of this the Cocoa Storyboard Agent crashed.
I fixed it by adding a guard statement:
class FooTableCell : UITableViewCell {
#IBOutlet private weak var checkmarkImageView: UIImageView!
override internal var selected : Bool {
didSet {
guard let imageView = checkmarkImageView else {
return
}
imageView.hidden = !selected
}
}
}