Swift 中项目左侧对齐的 collectionViewLayout

如何解决Swift 中项目左侧对齐的 collectionViewLayout

我有一个 collectionView，其中包含来自服务请求的图像，这些图像按 3 个元素显示。 我需要的是，当请求中只有一两个图像时，图像显示向左对齐，但屏幕显示图像居中。

    func collectionView(_ collectionView: UICollectionView,layout collectionViewLayout: UICollectionViewLayout,sizeforItemAt indexPath: IndexPath) -> CGSize {
        if imageFuelArray.count == 1{
            let padding: CGFloat =  10
            let collectionViewWidth = collectionView.frame.size.width - padding
            let collectionViewHeight = collectionView.frame.size.height - padding
            
            return CGSize(width: collectionViewWidth,height: collectionViewHeight)
        } else{
            let padding: CGFloat =  10
            let collectionViewWidth = collectionView.frame.size.width - padding
            let collectionViewHeight = collectionView.frame.size.height - padding
            
            return CGSize(width: collectionViewWidth/2,height: collectionViewHeight/2)
        }
    }

解决方法

尝试计算单元格的宽度，使其始终为可用宽度的 1/3：

func collectionView(_ collectionView: UICollectionView,layout collectionViewLayout: UICollectionViewLayout,sizeForItemAt indexPath: IndexPath) -> CGSize {
    let numberOfItemsPerRow: CGFloat = 3
    let spacingBetweenCells: CGFloat = 10
        
    let totalSpacing = (2 * spacingBetweenCells) + ((numberOfItemsPerRow - 1) * spacingBetweenCells)
        
    let width = (collectionView.bounds.width - totalSpacing) / numberOfItemsPerRow
    let height = collectionView.bounds.height - totalSpacing
        
    return CGSize(width: width,height: height)
}

,

我有这个功能

func getSizeVews(){
         if imageFuelArray.count > 6{
            self.collectionView.heightAnchor.constraint(equalToConstant: self.collectionView.contentSize.height+45).isActive = true
                              self.servicesTableView.heightAnchor.constraint(equalToConstant: self.servicesTableView.contentSize.height+70).isActive = true
                              
                              view.layoutSubviews()
         } else {
            self.collectionView.heightAnchor.constraint(equalToConstant: self.collectionView.contentSize.height).isActive = true
                   self.servicesTableView.heightAnchor.constraint(equalToConstant: self.servicesTableView.contentSize.height+70).isActive = true
                   
                   view.layoutSubviews()
        }
       
    }

那里有我的 collectionView 数据源和委托

extension ServicesStationViewController: UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView,numberOfItemsInSection section: Int) -> Int {
        imageFuelArray.count
    }
    
    func collectionView(_ collectionView: UICollectionView,cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: flCollectionVieCell,for: indexPath) as! FuelCollectionViewCell
        let fuel = imageFuelArray[indexPath.row]
        
        if let cepsaFuel = CepsaFeaturesFuel(key: Int(fuel) ?? 0) {
            let imgName = CepsaFeaturesFuel.featureFuelImageName(with: cepsaFuel.featuresFuelType)
            
            cell.fuelImageView?.image = UIImage(named: imgName!)
        }
        return cell
    }
    func collectionView(_ collectionView: UICollectionView,sizeForItemAt indexPath: IndexPath) -> CGSize {
        if imageFuelArray.count == 1{
            let padding: CGFloat =  10
            let collectionViewWidth = collectionView.frame.size.width - padding
            let collectionViewHeight = collectionView.frame.size.height - padding
            
            return CGSize(width: collectionViewWidth,height: collectionViewHeight)
        } else{
            let padding: CGFloat =  10
            let collectionViewWidth = collectionView.frame.size.width - padding
            let collectionViewHeight = collectionView.frame.size.height - padding
            
            return CGSize(width: collectionViewWidth/2,height: collectionViewHeight/2)
        }
    }
    
}