ios - 以编程方式选择 Collection View 单元格无法执行单元格的某些 isSelected 例程

Question

我有这段代码可以在选择单元格时更改单元格的颜色和字体样式。它工作正常，除了当我从父 View 的 init(frame:) 函数中手动选择它时。它应该将颜色更改为蓝色，将字体样式更改为粗体，当我从测试设备切换它时，它工作得非常好。但是，当我尝试以编程方式设置默认选定项时，它仅将样式更改为粗体，但颜色仍然与未选定的相同，即。灰色的。

这是单元格的类:

class ItemCollectionCell: UICollectionViewCell {

    @IBOutlet weak var titleLabel: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

    func setupCell(title: String)
    {
        titleLabel.text = title
        titleLabel.textColor = UIColor.gray
    }


    override var isSelected: Bool{
        didSet {
            titleLabel.textColor = isSelected ? UIColor.blue : UIColor.gray
            titleLabel.font = isSelected ? UIFont.boldSystemFont(ofSize: titleLabel.font.pointSize) : UIFont.systemFont(ofSize: titleLabel.font.pointSize)
        }
    }

}

其中包含 Collection View 的父 View :

class ItemsView: UIView, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout{

    /*
    // Only override draw() if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func draw(_ rect: CGRect) {
        // Drawing code
    }
    */

    let reuseableCellId = "itemCell"

    let nibItemCell = UINib(nibName: "ItemCollectionCell", bundle: nil)


    //Collection view for items
    lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
        cv.dataSource = self
        cv.delegate = self
        //Create subview (collection) for the menu buttons
        //Register cell's XIB and class
        cv.register(nibItemCell, forCellWithReuseIdentifier: reuseableCellId)
        //Set subview BG color
        cv.backgroundColor = UIColor.white
        cv.contentInsetAdjustmentBehavior = .never

        return cv
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        //Add subview
        self.addSubview(collectionView)

        //Set subview constraints
        self.addConstraintsWithFormat("H:|[v0]|", views: collectionView)
        self.addConstraintsWithFormat("V:|[v0]|", views: collectionView)

        let selectedPath = IndexPath(item: 0, section: 0)
        collectionView.selectItem(at: selectedPath, animated: false, scrollPosition: .centeredVertically)
    }

    //... all the other funcs
}

这里出了什么问题？我该如何解决？谢谢。

Answer 1

在选择单元格之前， Collection View 似乎没有重新加载。另外，您是否尝试过手动更新 isSelected？