Ios 计算属性字符串高度

我正在尝试将tableViewCell高度设置为单元格内

attributedString

的高度。然而，无论我做什么，它似乎没有正确的大小。这就是我到目前为止所尝试的

单元高度

//Convert description to NSAttributedString and get height
//width is equal to screen width - right and left offset
//at the end add the bottom and height offset to the cell height
return detailPetViewModel!.description
                .lineSpacing(spacing: 4)
                .heightWithConstrainedWidth(width: Sizes.screenWidth - 40) + 10

自定义单元格子类中的descLabel

//Customize descLabel
descLabel.font = FontFamily.Avenir.Regular.font(size: 16)
descLabel.textColor = UIColor(named: .SecondaryTextColor)

//Multiple lines
descLabel.numberOfLines = 0
descLabel.lineBreakMode = .byWordWrapping
descLabel.sizeToFit()

行间距扩展

extension String {
    func lineSpacing(spacing: CGFloat) -> NSAttributedString {

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = spacing

        let attributedString = NSMutableAttributedString(string: self)
        attributedString.addAttribute(NSParagraphStyleAttributeName, value:paragraphStyle, range:NSMakeRange(0, attributedString.length))
        return attributedString
    }
}

extension NSAttributedString {
    func heightWithConstrainedWidth(width: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)

        return boundingBox.height
    }

}

高度扩展

extension String {
    func lineSpacing(spacing: CGFloat) -> NSAttributedString {

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineSpacing = spacing

        let attributedString = NSMutableAttributedString(string: self)
        attributedString.addAttribute(NSParagraphStyleAttributeName, value:paragraphStyle, range:NSMakeRange(0, attributedString.length))
        return attributedString
    }
}

extension NSAttributedString {
    func heightWithConstrainedWidth(width: CGFloat) -> CGFloat {
        let constraintRect = CGSize(width: width, height: .greatestFiniteMagnitude)
        let boundingBox = self.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, context: nil)

        return boundingBox.height
    }

}

---

这是我使用的扩展名。您不必传入任何关于字体或行距的信息，因为属性字符串已经知道其值

extension NSAttributedString {

    func height(containerWidth: CGFloat) -> CGFloat {

        let rect = self.boundingRect(with: CGSize.init(width: containerWidth, height: CGFloat.greatestFiniteMagnitude),
                                     options: [.usesLineFragmentOrigin, .usesFontLeading],
                                     context: nil)
        return ceil(rect.size.height)
    }

    func width(containerHeight: CGFloat) -> CGFloat {

        let rect = self.boundingRect(with: CGSize.init(width: CGFloat.greatestFiniteMagnitude, height: containerHeight),
                                     options: [.usesLineFragmentOrigin, .usesFontLeading],
                                     context: nil)
        return ceil(rect.size.width)
    }
}

这样使用：

let height = detailPetViewModel!.description.height(containerWidth: Sizes.screenWidth - 40 + 10)

您只需使用

（NSAttributedString的实例）.size.height

e、 g

让a=NSAttributedString（字符串：“a字符串”，属性：[NSAttributedString.Key.font:UIFont.boldSystemFont（大小：14）]）
设高度=a.尺寸（）.高度

为什么不使用动态单元格高度的优势呢？您需要对示例中的语法做一点小的修改（否则，非常正确）：您使用了两个句点（detailPetViewModel！.description..height），而它应该是一个句点（detailPetViewModel！.description.height）。请注意“Font”属性必须在属性字符串中设置，否则计算将出错。考虑给定的宽度如何？