Horizontal scrolling collection view cells not resizing based on content width

问题

I have initialized the collection view like this:

 override init(frame: CGRect){
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        layout.itemSize = UICollectionViewFlowLayoutAutomaticSize
        layout.estimatedItemSize = CGSize(width: 100, height: 30)
        
        countryCollectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
        
        viewTitleLabel = UILabel()
        super.init(frame: frame)
        setupTableView()
        sortedDummyData = dummyData.sorted(by: <)
    }

And I return size as CGSize.zero:

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
//        return CGSize(width: 70, height: 30)
        return CGSize.zero
    }

This is how my cell is defined:

override init(frame: CGRect) {
        countryNameLabel = UILabel()
        countryUserCountLabel = UILabel()
        super.init(frame: frame)

        contentView.addSubview(countryNameLabel)
        countryNameLabel.translatesAutoresizingMaskIntoConstraints = false
        countryNameLabel.font = UIFont.boldSystemFont(ofSize: 13)
        countryNameLabel.textColor = .white
        
        contentView.addSubview(countryUserCountLabel)
        countryUserCountLabel.translatesAutoresizingMaskIntoConstraints = false
        countryUserCountLabel.font = UIFont.systemFont(ofSize: 13)
        countryUserCountLabel.textColor = .white
        
        NSLayoutConstraint.activate([
            countryNameLabel.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 5),
            countryNameLabel.heightAnchor.constraint(equalToConstant: 30),
            countryNameLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 5),
            countryNameLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -5),
//            countryNameLabel.widthAnchor.constraint(greaterThanOrEqualToConstant: 0),
//            countryNameLabel.widthAnchor.constraint(equalToConstant: 20),

            countryUserCountLabel.leadingAnchor.constraint(equalTo: countryNameLabel.trailingAnchor, constant: 5),
            countryUserCountLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 5),
            countryUserCountLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -5),
            countryUserCountLabel.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -5),
            countryUserCountLabel.heightAnchor.constraint(equalToConstant: 30),
            countryUserCountLabel.widthAnchor.constraint(equalToConstant: 40)
        ])
    }

This is the output I get:

回答1:

This update worked for me:

Returning non-zero cell size:

   func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: 70, height: 30)
//        return CGSize.zero
    }

Updated cell constraints:

        NSLayoutConstraint.activate([
            countryNameLabel.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 5),
            countryNameLabel.heightAnchor.constraint(equalToConstant: 30),
            countryNameLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 5),
            countryNameLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -5),
//            countryNameLabel.widthAnchor.constraint(greaterThanOrEqualToConstant: 0),
//            countryNameLabel.widthAnchor.constraint(equalToConstant: 20),

            countryUserCountLabel.leadingAnchor.constraint(equalTo: countryNameLabel.trailingAnchor, constant: 5),
            countryUserCountLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 5),
            countryUserCountLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -5),
            countryUserCountLabel.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: -5),
            countryUserCountLabel.heightAnchor.constraint(equalToConstant: 30),

// Removed the width constraint
//            countryUserCountLabel.widthAnchor.constraint(equalToConstant: 40)
        ])

来源：https://stackoverflow.com/questions/65680963/horizontal-scrolling-collection-view-cells-not-resizing-based-on-content-width

标签

ios

swift

uicollectionview

uicollectionviewcell

uicollectionviewlayout