In Collectionview How to Set Colors According to Selection

in Collectionview how to set colors according to selection?

In your viewDidLoad reload the collectionView and after that explicitly select the first cell like this way.

collView.reloadData()
let indexPath = NSIndexPath(forItem: 0, inSection: 0)
collView.selectItemAtIndexPath(indexPath, animated: true, scrollPosition: .None)

Note : Now there is no need to add code of color changing inside your cellForIteamAtIndexPath remove that code.

Set selected color of cell in UiCollectionView in swift

For two different colors based on selected state of the cell, you may need to subclass your UICollectionViewCell like this:

import UIKit 

class YourCollectionViewCell: UICollectionViewCell {

    @IBOutlet weak var imageView: UIImageView! // for example - some UI element inside cell ...

    override var isSelected: Bool {
        didSet {
            self.contentView.backgroundColor = isSelected ? UIColor.blue : UIColor.yellow
            self.imageView.alpha = isSelected ? 0.75 : 1.0
        }  
      }
    }

// and below you will have your original code

class YourViewController: UICollectionViewController {

... etc

Answering your question - for exceptional style of the first cell:

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

        let cell = collectionView.dequeueReusableCell ... 

        if(indexPath.row == 0) { //for first cell in the collection
            cell.backgroundColor = UIColor.orange
        } else {
            cell.backgroundColor = UIColor.green
        }

How to change Color of cell in UiCollectionView if just two can be selected

I'd do it this way:

1. Use custom UICollectionViewCell subclass (without button because collection view cell handles selection itself)

2. in this cell class override isSelected property like this:

   override var isSelected: Bool {
       didSet {
           // set color according to state
           self.backgroundColor = self.isSelected ? .blue : .clear 
       }
   }
   

3. In class which controls your collectionView perform collectionView.allowsMultipleSelection = true

4. In your UICollectionViewDelegate implement method (which will prevent selection of more than two cells at a time):

   func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
       return (collectionView.indexPathsForSelectedItems?.count ?? 0) < 2
   }
   

This way you don't need a button inside the cell.

how to change cell background colour on selected item in UICollectionView and change other Cell colour to default in swift

Create a variable inside the vc

var currentSelected:Int?

then inside cellForItemAt

cell.backgroundColor = currentSelected == indexPath.row ? UIColor.green : UIColor.clear

finally didSelectItemAt

currentSelected = indexPath.row
collectionView.reloadData()

Don't depend on isSelected as cells are dequeued and when you scroll you'll get unexpected results

IOS Swift CollectionView How can I set the correct background color on index

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CategoriesCVC", for: indexPath) as! CategoriesCVC
        cell.items.tag = indexPath.row
        cell.items.setTitle(categoryTypes[indexPath.row], for: .normal)

        if categoryTypes[indexPath.row] == "All" && indexPath.row == CategoryIndex {

            cell.items.backgroundColor = UIColor(hexString: BlueBackground)
            cell.items.setTitleColor(.white, for: .normal)
        } else {
            // set your normal cell color here
            cell.items.backgroundColor = UIColor(hexString: NormalCellColor)
            cell.items.setTitleColor(.normalTitleColoe, for: .normal)
     }
        return cell
}

Since collection view uses the dequeued cell, it takes the old cell background. that is blue color. if you revert the cell color in the else block, that will fix your issues

if you want to do in more Professional way. on cell prepareForReuse, do your cleanups.

override open func prepareForReuse() {
    super.prepareForReuse()
    // Set your default background color, title color etc
}

Change label color when collectionView Cell is selected in Swift iOS

First, you should not be adding subviews in cellForItemAt ... cells are reused, and you end up adding the subviews multiple times in each cell.

Instead, add your subviews in your cell class when it is instantiated.

Then, add this to your cell class:

override var isSelected: Bool {
    didSet {
        label.textColor = isSelected ? .white : .black
    }
}

No need to do anything in your controller on didSelectItemAt or didDeselectItemAt

---

Edit -- here is a very simple example...

The cell class:

class MyCardCell: UICollectionViewCell {
    let label: UILabel = {
        let v = UILabel()
        return v
    }()
    let cardView: UIView = {
        let v = UIView()
        return v
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    func commonInit() -> Void {
        
        cardView.backgroundColor = UIColor(red:0.00, green:0.00, blue:0.00, alpha:0.02)
        cardView.layer.cornerRadius = 8
        cardView.layer.shadowOffset = CGSize(width: 0.2, height: 0.2)
        cardView.layer.shadowRadius = 1
        cardView.layer.shadowOpacity = 0.4
        cardView.layer.borderColor = CGColor(red:0.00, green:0.00, blue:0.00, alpha:0.2)
        cardView.layer.borderWidth = 0.4
        cardView.clipsToBounds = true
        
        label.textAlignment = .center
        label.textColor = UIColor(red:0.00, green:0.00, blue:0.00, alpha:0.8)
        label.font = UIFont.systemFont(ofSize: 9, weight: .semibold)

        [cardView, label].forEach { v in
            v.translatesAutoresizingMaskIntoConstraints = false
        }
        cardView.addSubview(label)
        contentView.addSubview(cardView)
        
        let g = contentView.layoutMarginsGuide
        
        NSLayoutConstraint.activate([
            
            cardView.topAnchor.constraint(equalTo: g.topAnchor),
            cardView.leadingAnchor.constraint(equalTo: g.leadingAnchor),
            cardView.trailingAnchor.constraint(equalTo: g.trailingAnchor),
            cardView.bottomAnchor.constraint(equalTo: g.bottomAnchor),

            label.centerYAnchor.constraint(equalTo: cardView.centerYAnchor),
            label.leadingAnchor.constraint(equalTo: cardView.leadingAnchor, constant: 12.0),
            label.trailingAnchor.constraint(equalTo: cardView.trailingAnchor, constant: -12.0),

        ])
    
    }
    
    override var isSelected: Bool {
        didSet {
            label.textColor = isSelected ? .white : .black
            // see the difference between setting
            //      cardView.backgroundColor
            //  or
            //      contentView.backgroundColor
            cardView.backgroundColor = isSelected ? UIColor(red: 0.99, green: 0.71, blue: 0.25, alpha: 1.00) : UIColor(red:0.00, green:0.00, blue:0.00, alpha:0.02)
            //contentView.backgroundColor = isSelected ? UIColor(red: 0.99, green: 0.71, blue: 0.25, alpha: 1.00) : UIColor(red:0.00, green:0.00, blue:0.00, alpha:0.02)
        }
    }
}

and a sample view controller class:

class TestCardCollectionVC: UIViewController {
    
    var collectionView: UICollectionView!

    var type: [String] = ["All","Coffee Shops","Pizza Places","Restaurants","Desserts"]

    override func viewDidLoad() {
        super.viewDidLoad()
        
        let fl = UICollectionViewFlowLayout()
        fl.scrollDirection = .horizontal
        fl.minimumLineSpacing = 0
        fl.minimumInteritemSpacing = 0
        fl.estimatedItemSize = CGSize(width: 50, height: 40)

        collectionView = UICollectionView(frame: .zero, collectionViewLayout: fl)
        
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(collectionView)
        
        let g = view.safeAreaLayoutGuide
        NSLayoutConstraint.activate([
            collectionView.topAnchor.constraint(equalTo: g.topAnchor),
            collectionView.leadingAnchor.constraint(equalTo: g.leadingAnchor),
            collectionView.trailingAnchor.constraint(equalTo: g.trailingAnchor),
            collectionView.heightAnchor.constraint(equalToConstant: 40.0)
        ])

        collectionView.backgroundColor = .systemBackground
        
        collectionView.register(MyCardCell.self, forCellWithReuseIdentifier: "cardCell")

        collectionView.dataSource = self
        collectionView.delegate = self
    }
    
}

extension TestCardCollectionVC: UICollectionViewDataSource, UICollectionViewDelegate {
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return type.count
    }
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let c = collectionView.dequeueReusableCell(withReuseIdentifier: "cardCell", for: indexPath) as! MyCardCell
        c.label.text = type[indexPath.item]
        return c
    }

}

The output on launch (no cell selected):

selecting the 3rd cell:

selecting the 4th cell:

How to change the background color of a custom Collection View cell in swift iOS?

You can use selectedBackgroundView property of UICollectionViewCell for that, inside cellForItemAt indexPath set that property and now when you select cell it will automatically change the backgroundColor of that cell.

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
     let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! PlaceCollectionViewCell
     //Your other code

     //Add code to set selectedBackgroundView property
     let view = UIView(frame: cell.bounds)
     // Set background color that you want
     view.backgroundColor = UIColor(colorLiteralRed: 0.278, green: 0.694, blue: 0.537, alpha: 1.00) 
     cell.selectedBackgroundView = view
     return cell
}

Using this now there is no need to change backgroundColor of cell in didSelectItemAt indexPath it will work automatically and change backgroundColor for that selected cell.

How change color of a selected item?

In the document, there is a section shows you how to change color of a selected item.

CollectionView has a Selected VisualState that can be used to initiate a visual change to the selected item in the CollectionView:

In your case, change the backgroundColor of stacklayout would work:

<ContentPage.Resources>
    <Style TargetType="StackLayout">
        <Setter Property="VisualStateManager.VisualStateGroups">
            <VisualStateGroupList>
                <VisualStateGroup x:Name="CommonStates">
                    <VisualState x:Name="Normal" />
                    <VisualState x:Name="Selected">
                        <VisualState.Setters>
                            <Setter Property="BackgroundColor"
                                    Value="LightSkyBlue" />
                        </VisualState.Setters>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateGroupList>
        </Setter>
    </Style>
</ContentPage.Resources>

<CollectionView SelectionMode="Single">
    <CollectionView.ItemsSource>
        <x:Array Type="{x:Type x:String}">
            <x:String>Baboon</x:String>
            <x:String>Capuchin Monkey</x:String>
            <x:String>Blue Monkey</x:String>
            <x:String>Squirrel Monkey</x:String>
            <x:String>Golden Lion Tamarin</x:String>
            <x:String>Howler Monkey</x:String>
            <x:String>Japanese Macaque</x:String>
        </x:Array>
    </CollectionView.ItemsSource>

    <CollectionView.ItemTemplate>
        <DataTemplate>
            <StackLayout>
                <Label Text="{Binding .}" TextColor="Black"/>
            </StackLayout>
        </DataTemplate>

    </CollectionView.ItemTemplate>

</CollectionView>

Another way is binding the BackgroundColor with the property in your ViewModel and change it when the item is selected:

 <Label Text="{Binding .}" TextColor="Black" BackgroundColor="{Binding backColor}"/>

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