How to add three or more collectionViews in any viewController

Question

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

        if collectionView == thisSeasonCollectionView {
            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as UICollectionViewCell

            let imageView = cell.viewWithTag(1) as! UIImageView

            let url = NSURL(string: URLArrayStringThisSeason[indexPath.row])

            let placeholderImage = UIImage(named: "Rectangle")!

            let filter = AspectScaledToFillSizeWithRoundedCornersFilter(
                size: imageView.frame.size,
                radius: 0
            )

            imageView.af_setImage(withURL: url as! URL, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2)
            )
            cell.layer.cornerRadius = 3.0

            return cell
        }
        else if collectionView == whatsNewCollectionView {

            let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as UICollectionViewCell

            let imageView = cell.viewWithTag(1) as! UIImageView

            let url = NSURL(string: URLArrayStringRecents[indexPath.row])

            let placeholderImage = UIImage(named: "Rectangle")!

            let filter = AspectScaledToFillSizeWithRoundedCornersFilter(
                size: imageView.frame.size,
                radius: 0
            )

            imageView.af_setImage(withURL: url as! URL, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2)
            )

            cell.layer.cornerRadius = 3.0

            return cell
        }
    }

Why doesn't this work? I wish to try to link 3 collection view each from a different tableView Cell to this swift file but it seems like there can only be two. The code works fine if I replace 'else if' with 'else' for some reason.

Edit:

How do I edit the return of cell count:

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

        if collectionView == thisSeasonCollectionView {
            return URLArrayStringThisSeason.count
        }else if collectionView == whatsNewCollectionView {
            return URLArrayStringRecents.count
        }else if collectionView == labelCollectionView {
            return URLArrayStringLabel.count
        }

    }

Compare http://stackoverflow.com/questions/30189505/missing-return-uitableviewcell. — Martin R, Oct 15 '16 at 15:58

Rashwan L · Accepted Answer · 2016-10-15T15:34:21.827

Change your code to the following:

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as UICollectionViewCell

    if collectionView == thisSeasonCollectionView {
        let imageView = cell.viewWithTag(1) as! UIImageView

        let url = NSURL(string: URLArrayStringThisSeason[indexPath.row])

        let placeholderImage = UIImage(named: "Rectangle")!

        let filter = AspectScaledToFillSizeWithRoundedCornersFilter(
            size: imageView.frame.size,
            radius: 0
        )

        imageView.af_setImage(withURL: url as! URL, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2)
        )
        cell.layer.cornerRadius = 3.0
    }
    else if collectionView == whatsNewCollectionView {
        let imageView = cell.viewWithTag(1) as! UIImageView

        let url = NSURL(string: URLArrayStringRecents[indexPath.row])

        let placeholderImage = UIImage(named: "Rectangle")!

        let filter = AspectScaledToFillSizeWithRoundedCornersFilter(
            size: imageView.frame.size,
            radius: 0
        )

        imageView.af_setImage(withURL: url as! URL, placeholderImage: placeholderImage, filter: filter, imageTransition: .crossDissolve(0.2)
        )

        cell.layer.cornerRadius = 3.0
    }

    return cell
 }

Make the return cell at the end since you will only hit one of your statements and all statements needs to return a cell, so no need to return cell on three different places, it´s enough to place it in the end. And it´s not necessary to add the let cell = collectionView.dequeu... two times, it´s enough with one time.

As you have done it is fine, if you only have two values that you want to check use `if else` only. — Rashwan L, Oct 15 '16 at 15:49
hmm, I've updated the question above. I've got three collectionViews that I need to count for the cells. — Ler Ws, Oct 15 '16 at 15:51
If you have three conditions for your cell to, then you can use the same. — Rashwan L, Oct 15 '16 at 15:54

score 0 · Answer 2 · answered Oct 15 '16 at 15:19

0

Not all control paths in above code return a cell. Add another return after 'else if' body

answered Oct 15 '16 at 15:19

Khurram Shehzad

261
3
12

that didnt work too. There's nothing to return outside the else if body. And all bodies have a return cell. – Ler Ws Oct 15 '16 at 15:23
@LerWs then change the `else if ...` to `else`. – luk2302 Oct 15 '16 at 15:30
I need to have three collection views. I'm setting it to else if so that I can add another else if for another collectionView – Ler Ws Oct 15 '16 at 15:31

score 0 · Answer 3 · answered Oct 15 '16 at 15:35

Your code boils down to

function doSomething(a : Int) -> String {
    if a == 1 {
        return "something";
    } else if a == 2 {
        return "somethingElse";
    }
}

The compiler complains because what happens if a is 3? The method will not return anything. You might know a will never be 3, but the compiler does not know that.

Therefore either change the else if ... to a simple else to make the function always return something OR return something after the else if.

score 0 · Answer 4 · answered Oct 15 '16 at 15:53

According to the comments you posted on the other answers, you have three (and potentially more) collection views and wish to have a code structure like this:

if collectionView == collectionView1 {
    // code that returns some cell
} else if collectionView == collectionView2 {
    // code that returns some other cell
} else if collectionView == collectionView3 {
    // code that returns yet another cell
}

And the reason why you use an else if instead of an else is because you want to add more else ifs later on.

Then I think, calling fatalError is the best solution for you.

if collectionView == collectionView1 {
    // code that returns some cell
} else if collectionView == collectionView2 {
    // code that returns some other cell
} else if collectionView == collectionView3 {
    // code that returns yet another cell
}
fatalError("Please add another else if to handle the cell of collection view!")

Not only does this removes the "no all code path returns a value" error, it also reminds you if you forgot to add an else if!

This solution can also be applied to the other datasource methods as well!

score 0 · Answer 5 · answered Oct 15 '16 at 16:14

Thanks guys, I'll try the switch method too next but for now I've found a pretty good method:

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        let cellCount = 0

        if collectionView == thisSeasonCollectionView {
            let cellCount = URLArrayStringThisSeason.count
            return cellCount
        }else if collectionView == whatsNewCollectionView {
            let cellCount = URLArrayStringRecents.count
            return cellCount
        }else if collectionView == labelCollectionView {
            let cellCount = URLArrayStringLabel.count
            return cellCount
        }
        return cellCount
    }

How to add three or more collectionViews in any viewController

5 Answers5