collectionview are repeating inside a tableview cell

Question

i am using a collectionview inside a tablview cell, in which collectionview cells are having an imageview on which images are displaying from the array of URLs in cellForItemAtIndexPath. I am calling webservice inside tableview cell class to getting array of URLs. My problem is that whenever i scrolls down or up tableview, collectionview cells are repeating, images of collectionview are repeating itself. so how to get rid out of this.

My Code is as follows -

inside response of webservice

let imgList : NSArray = arrReponseDetails.value(forKey: "imageList") as! NSArray
        self.arrImgUrls.removeAll()
        for dict in imgList[0] as! NSArray {
            let dictionary = dict as! NSDictionary
            let strUrl : String = dictionary["url_highRes"] as! String
            let url : URL = URL(string: strUrl)!
            self.arrImgUrls.append(url)
        }
        self.collectionView.reloadData()

code inside of cellForItemAtIndexPath

let cell : CollectionCell =  collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionCell

let url : URL = self.arrImgUrls[indexPath.row]
cell.imgSticker.sd_setShowActivityIndicatorView(true)
cell.imgSticker.sd_setIndicatorStyle(.gray)
cell.imgSticker.sd_setImage(with: url, placeholderImage: nil)
cell.imgSticker.contentMode = .scaleAspectFit
return cell

You should not call Webservice within cell class, It may get called every time cell load — Abhishek, Sep 11 '17 at 07:32
actually each collectionview representing distinct set of Images , i am passing a unique key from ViewController class to that tableview cell from which i am able to call webservice and then i am getting an array of urls as i posted in question. it will become too heavy for app if i call both the service in a single viewcontroller class — iNoob, Sep 11 '17 at 07:38
Use an image caching library to remove flickering and also Implement some logic so webservice will get called only once for each Row, Not like each time when you scroll — Abhishek, Sep 11 '17 at 09:18

score 2 · Accepted Answer · answered Sep 11 '17 at 07:36

2

I am not getting much insight from your question but i think problem is with caching of image with reusable cell.

Simply implement prepareForReuse() method in collectionView Cell class(CollectionCell).

override func prepareForReuse() {
    super.prepareForReuse()
    self.imgSticker = nil
}

Reference of prepareForReuse()

answered Sep 11 '17 at 07:36

technerd

14,144
10
61
92

i have already added this. for now images are fluctuating means old cell's images are appeared for a while then new images replaces them. and this process is repeating as i scrolls tablview – iNoob Sep 11 '17 at 07:44

score 0 · Answer 2 · answered Sep 11 '17 at 08:46

You need to clear it out the old content from the cell's view before setting new one as in some case some content might be left and that reported issue occurs.

func collectionView(collectionView: UICollectionView, 
      cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell 
    {
        let cell : CollectionCell =  collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionCell

        cell.imageView.image = nil;  //Remove the image (cache one)
    }

Hope this helps!!

score 0 · Answer 3 · answered Sep 11 '17 at 13:33

0

Hi You should add the below code on CollectionCell class:

- (void)prepareForReuse
{
    [super prepareForReuse];
    [[self imgSticker] setImage:nil];
}

Note: It would be better if you can set the placeholder image also.

answered Sep 11 '17 at 13:33

Rakesh Tatekonda

91
8

i have already added this. for now images are fluctuating, means old cell's images are appeared for a while then new images replaces them. and this process is repeating as i scrolls tablview – iNoob Sep 11 '17 at 13:47
did you set image to nil and did you even set the placeholder image.? – Rakesh Tatekonda Sep 11 '17 at 13:50
yes... image is set to nil and placeholder images i'm not using so it is also set to nil – iNoob Sep 11 '17 at 13:56
can you share the code snippet of code you have added – Rakesh Tatekonda Sep 11 '17 at 13:58

score -1 · Answer 4 · answered Sep 11 '17 at 08:33

I wouldn' use colelctionView inside tableView, it's really strange approach. I used to do it myself for the first time and it got me into trouble. Consider changing the logic for collectionView with custom layout...

But to answer your question, it's better to use this approach (check out this answer)

just set in the CellForRow the imageView method according to this answer:

https://stackoverflow.com/a/27712427/5774854

collectionview are repeating inside a tableview cell

4 Answers4