我想计算文本的高度以获得集合视图单元格的估计高度。我在collectionViewLayout函数中使用以下代码;

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    if let messageText = messages[indexPath.row]?.text {

        let size = CGSize(width: view.frame.width, height: 1000)
        let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
        let estimatedFrame = NSString(string: messageText).boundingRect(with: size, options: options, attributes: [NSAttributedStringKey.font: UIFont.systemFont(ofSize: 17)], context: nil)
        return CGSize(width: view.frame.width, height: estimatedFrame.height + 20)
    }

    return CGSize(width: view.frame.width, height: 100)
}

这适用于系统字体,但不适用于项目中的自定义字体。问题是estimatedFrame不等于系统字体的结果。我认为问题在于选项的参数:attributes。有没有像UIFont.systemFont(ofSize: 17)这样的自定义字体的方法?

最佳答案

如果我没看错你的问题,你想:

UIFont(name: "yourCustomFontNameString", size: 17)

所以:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    if let messageText = messages[indexPath.row]?.text {

        let size = CGSize(width: view.frame.width, height: 1000)
        let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
        let estimatedFrame = NSString(string: messageText).boundingRect(with: size, options: options, attributes: [NSAttributedStringKey.font: UIFont(name: "yourCustomFontNameString", size: 17)], context: nil)
        return CGSize(width: view.frame.width, height: estimatedFrame.height + 20)
    }

    return CGSize(width: view.frame.width, height: 100)
}

关于swift - 如何声明NSAttributedStringKey.font为自定义字体?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/47145432/

10-10 14:22
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