Question

• I don’t know how to set category collection view first cell to be selected in default state

Setup

1. Register your collection view cell(I use storyboard + XIB)
   • register
   • delegate/datasource assign to self(ViewController)
   • UICollectionViewFlowLayout
2. Basic collection view delegate/datasource method

   • numberOfItemsInSection

   • cellForItemAt

     func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
         guard let item = categoryCollectionView.dequeueReusableCell(withReuseIdentifier: CategoryCollectionViewCell.reuseIdentifier, for: indexPath) as? CategoryCollectionViewCell else {
             return UICollectionViewCell()
         }
         let category = categories[indexPath.row]
         item.configure(with: category)
     
         return item
     }
     

   • didSelectItemAt

3. Connect your UI(IBOutlet) into collection view cell

CellModel

<aside> 💡 Here because I’m not familiar with model, so didn’t come up with this solution first

</aside>

1. Create CategoryCellModel

   struct CategoryCellModel {
       let category: **Category**
       var isSelected: Bool = false
   }
   

2. Change your property to this new model struct

   var categories = [**CategoryCellModel**]() {
       didSet {
           DispatchQueue.main.async {
               self.categoryCollectionView.reloadData()
           }
       }
   }
   

3. Configure your data status(Here you set the first one isSelected to true)

   ProductService.shared.loadProductType(id: user.member_id, pwd: user.member_pwd) { responseCategories in
       var **isFirstCategory** = true
       self.categories = responseCategories.**map** {
           if isFirstCategory {
               isFirstCategory = false
               return **CategoryCellModel(category: $0, isSelected: true)**
           } else {
               return **CategoryCellModel(category: $0)**
           }
       }
   }
   

4. Set isItemSelected property for collection view cell

   var isItemSelected: Bool = false {
       didSet {
           indicatorView.alpha = isItemSelected ? 1 : 0
           categoryLabel.textColor = isItemSelected ? UIColor(hex: "#5F9EA0") : .systemGray2
       }
   }
   

5. Update your cellForItemAt method

   func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
       guard let item = categoryCollectionView.dequeueReusableCell(withReuseIdentifier: CategoryCollectionViewCell.reuseIdentifier, for: indexPath) as? CategoryCollectionViewCell else {
           return UICollectionViewCell()
       }
       let category = categories[indexPath.row]
       item.configure(with: category)
       **item.isItemSelected = category.isSelected**
   
       return item
   }
   

6. Add style change on didSelectItemAt

   func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
       // UI
       **for (index, _) in categories.enumerated() {
           categories[index].isSelected = index == indexPath.item
       }**
   }
   

Result