如何在 UICollectionView 单元格中获取 UIImageView 的帧大小

Question

我正在尝试获取 UICollectionViewCell 中 UIImageView 的帧大小。我目前尝试使用 thumbnailImageView.frame.size 来实现此目的，但无论我从何处调用此方法，此 returns (0.0, 0.0) 都是如此。

我想这样做的原因是在图像视图中圆化图像的边缘，但是因为我正在使用 .scaleAspectFit 我需要知道帧大小和图像大小才能正确圆角.

下面是单元格 class:

class SomeCollectionViewCell: UICollectionViewCell {

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

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    let thumbnailImageView: UIImageView = {
        let imageView = UIImageView()
        imageView.contentMode = .scaleAspectFit
        return imageView
    }()

    private func setLabel(label: UILabel, textSize: CGFloat = 15.0, textColour: UIColor = UIColor.black) -> UILabel {
        label.textColor = textColour
        label.textAlignment = .center
        label.font = label.font.withSize(textSize)
        return label
    }

    var firstLabel: UILabel = UILabel()
    var secondLabel: UILabel = UILabel()
    var thirdLabel: UILabel = UILabel()

    func setupViews() {
        firstLabel = setLabel(label: firstLabel)
        secondLabel = setLabel(label: secondLabel)
        thirdLabel = setLabel(label: thirdLabel)

        addSubview(thumbnailImageView)
        addSubview(firstLabel)
        addSubview(secondLabel)
        addSubview(thirdLabel)

        addConstraintWithFormat(format: "V:|-25-[v0(125)]-[v1(16)]-[v2(16)]-[v3(17)]-25-|", views: thumbnailImageView, firstLabel, secondLabel, thirdLabel)
        addConstraintWithFormat(format: "H:|[v0]|", views: thumbnailImageView)
        addConstraintWithFormat(format: "H:|[v0]|", views: firstLabel)
        addConstraintWithFormat(format: "H:|[v0]|", views: secondLabel)
        addConstraintWithFormat(format: "H:|[v0]|", views: thirdLabel)

    }

}

extension UIView {
    func addConstraintWithFormat(format: String, views: UIView...) -> Void {
        var viewDictionary = [String : UIView]()
        for (index, view) in views.enumerated() {
            let key = "v\(index)"
            viewDictionary[key] = view
            view.translatesAutoresizingMaskIntoConstraints = false
        }
        NSLayoutConstraint.activate(NSLayoutConstraint.constraints(withVisualFormat: format, options: NSLayoutFormatOptions(), metrics: nil, views: viewDictionary))
    }
}

Answer 1

也许这就是你想要的，试试吧：

print(cell.photo?.image.size)

Answer 2

还有一种可能打印(cell.frame.size)

Answer 3

所以解决问题的办法就是用这个方法：

func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
    }

此方法用于告诉委托指定的单元格即将显示在集合视图中，此时，它已被赋予边界。

如何在 UICollectionView 单元格中获取 UIImageView 的帧大小

How to get the frame size of a UIImageView in a UICollectionView cell

uiimageview

uicollectionview

uicollectionviewcell

swift