Swift:字符串 - 计算高度的第一个字符位置？

Question

我想缩短长字符串，以“查看更多...”结尾。

如果字符串没有新行，一切顺利。

---

"The cat ate the cake and went outside the house, without any problems. Then the next day something really bad happened. The owner kicked the cat out, and the little animal had no chance to go back."

成为

"The cat ate the cake and went outside the house, without any problems. Then the see more..."

---

但除此之外，我也想限制高度。这样字符串的高度最大为 200pt，如下所示:

2 new lines

>

1 new line

3 new lines

>

>

0 new line

应该变成

2 new lines

>

1 new line

See more...

---

我如何确定应该在哪个字符后放置“查看更多...”文本？

代码:

func shorten(maxWidth : CGFloat) -> NSMutableAttributedString {


        let font = UIFont.preferredFont(forTextStyle: UIFont.TextStyle.body)
        // If height is more than 200pt
        if self.height(withConstrainedWidth: maxWidth, font: font) > 200 {
            // Here.. how?
           return finalString
        }

        // If char is more than 400
        if self.count > 400 {
            // BLA BLA CUT TEXT
            return finalString
        }

        let finalString = NSMutableAttributedString(string: self, attributes: [NSAttributedString.Key.font : font])

        return finalString
    }

Answer 1

我强烈建议您不要将 see more... 作为纯字符串放在您的文本中。

更好的方法是在 UIButton 标签后立即添加 see more... 文本。

在这种情况下，您可以轻松地操纵它的位置、形式、UI 等