Ios 如何使用PDFKit获取段落高度

我正在使用iOS PDFKit编写pdf。通常，我可以通过执行以下操作获得单个文本项（如标题）的高度：

return titleStringRect.origin.y + titleStringRect.size.height

其中titleStringRect是包含字符串的CGRect。返回的值是该文本底部的y坐标，以便我知道从何处开始写入下一行文本。 我还没有找到一种方法来知道一段的结尾。我找到的解决办法是只做一个足够大的CGRect，这段文字肯定会适合。 我需要确切地知道CGRect的高度应该基于将写入其中的字符串。这是我的密码：

    func addParagraph(pageRect: CGRect, textTop: CGFloat, text: String) {

        let textFont = UIFont(name: "Helvetica", size: 12)
        let backupFont = UIFont.systemFont(ofSize: 12, weight: .regular)

        // Set paragraph information. (wraps at word breaks)
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .natural
        paragraphStyle.lineBreakMode = .byWordWrapping

        // Set the text attributes
        let textAttributes = [
            NSAttributedString.Key.paragraphStyle: paragraphStyle,
            NSAttributedString.Key.font: textFont ?? backupFont
        ]

        let attributedText = NSAttributedString(
            string: text,
            attributes: textAttributes
        )

        let textRect = CGRect(
            x: 50.0,
            y: textTop,
            width: pageRect.width - 100,
            height: pageRect.height - textTop - pageRect.height / 5.0
        )
        attributedText.draw(in: textRect)
    }

正如您所看到的，上面的代码只生成一个CGRect，它是前面文本下方空间的1/5，而不管段落实际有多少行。 我尝试平均每行的字符数，以估计段落将有多少行，但这是不可靠的，肯定是一个黑客。

---

我需要的是addPagement函数返回段落底部的y坐标，以便我知道从何处开始编写下一段内容

我最终找到了解决这个问题的方法，而且非常简单。我将发布代码，然后向其他有此问题的人解释

let paragraphSize = CGSize(width: pageRect.width - 100, height: pageRect.height)
let paragraphRect = attributedText.boundingRect(with: paragraphSize, options: NSStringDrawingOptions.usesLineFragmentOrigin, context: nil)

首先定义一个具有一定宽度和高度的CGSize。将宽度设置为您希望段落的宽度，并将高度设置为适合内容的较大值。然后打电话

AttributeText.boundingRect（带：段落大小，选项：NSStringDrawingOptions.usesLineFragmentOrigin，上下文：nil）

其中AttributeText是段落内容。boundingRect方法返回一个CGRect，该CGRect是将内容放入所需的大小，但仅此而已。现在您可以返回段落的底部。此方法不会更改宽度，除非它无法将字符串调整到您提供的高度。就我而言，这是完美的。以下是完整的代码：

 func addParagraph(pageRect: CGRect, textTop: CGFloat, paragraphText: String) -> CGFloat {

        let textFont = UIFont(name: "Helvetica", size: 12)
        let backupFont = UIFont.systemFont(ofSize: 12, weight: .regular)

        // Set paragraph information. (wraps at word breaks)
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .natural
        paragraphStyle.lineBreakMode = .byWordWrapping

        // Set the text attributes
        let textAttributes = [
            NSAttributedString.Key.paragraphStyle: paragraphStyle,
            NSAttributedString.Key.font: textFont ?? backupFont
        ]

        let attributedText = NSAttributedString(
            string: paragraphText,
            attributes: textAttributes
        )

        // determine the size of CGRect needed for the string that was given by caller
        let paragraphSize = CGSize(width: pageRect.width - 100, height: pageRect.height)
        let paragraphRect = attributedText.boundingRect(with: paragraphSize, options: NSStringDrawingOptions.usesLineFragmentOrigin, context: nil)

        // Create a CGRect that is the same size as paragraphRect but positioned on the pdf where we want to draw the paragraph
        let positionedParagraphRect = CGRect(
            x: 50,
            y: textTop,
            width: paragraphRect.width,
            height: paragraphRect.height
        )

        // draw the paragraph into that CGRect
        attributedText.draw(in: positionedParagraphRect)

        // return the bottom of the paragraph
        return positionedParagraphRect.origin.y + positionedParagraphRect.size.height
    }

---

我最终找到了解决这个问题的方法，而且非常简单。我将发布代码，然后向其他有此问题的人解释

let paragraphSize = CGSize(width: pageRect.width - 100, height: pageRect.height)
let paragraphRect = attributedText.boundingRect(with: paragraphSize, options: NSStringDrawingOptions.usesLineFragmentOrigin, context: nil)

首先定义一个具有一定宽度和高度的CGSize。将宽度设置为您希望段落的宽度，并将高度设置为适合内容的较大值。然后打电话

AttributeText.boundingRect（带：段落大小，选项：NSStringDrawingOptions.usesLineFragmentOrigin，上下文：nil）

其中AttributeText是段落内容。boundingRect方法返回一个CGRect，该CGRect是将内容放入所需的大小，但仅此而已。现在您可以返回段落的底部。此方法不会更改宽度，除非它无法将字符串调整到您提供的高度。就我而言，这是完美的。以下是完整的代码：

 func addParagraph(pageRect: CGRect, textTop: CGFloat, paragraphText: String) -> CGFloat {

        let textFont = UIFont(name: "Helvetica", size: 12)
        let backupFont = UIFont.systemFont(ofSize: 12, weight: .regular)

        // Set paragraph information. (wraps at word breaks)
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .natural
        paragraphStyle.lineBreakMode = .byWordWrapping

        // Set the text attributes
        let textAttributes = [
            NSAttributedString.Key.paragraphStyle: paragraphStyle,
            NSAttributedString.Key.font: textFont ?? backupFont
        ]

        let attributedText = NSAttributedString(
            string: paragraphText,
            attributes: textAttributes
        )

        // determine the size of CGRect needed for the string that was given by caller
        let paragraphSize = CGSize(width: pageRect.width - 100, height: pageRect.height)
        let paragraphRect = attributedText.boundingRect(with: paragraphSize, options: NSStringDrawingOptions.usesLineFragmentOrigin, context: nil)

        // Create a CGRect that is the same size as paragraphRect but positioned on the pdf where we want to draw the paragraph
        let positionedParagraphRect = CGRect(
            x: 50,
            y: textTop,
            width: paragraphRect.width,
            height: paragraphRect.height
        )

        // draw the paragraph into that CGRect
        attributedText.draw(in: positionedParagraphRect)

        // return the bottom of the paragraph
        return positionedParagraphRect.origin.y + positionedParagraphRect.size.height
    }