How to limit UILabel's max characters

Question

I want to limit UILabel.text in 8 Chinese word or 16 English word, and if the text is larger than this, use "..." to replace the redundant place.

I tried to count String size, but I don't know how to deal with both English words and Chinese words. Because is I count bytes by utf8, the Chinese word would be triple than English words. (Considering the label might have both Chinese word and English words, it's hard to calculate.)

for example:

1."Batman like cat Woman and Alfred." should look like "Batman like cat..."

2."蝙蝠侠喜欢猫女和阿福" should look like "蝙蝠侠喜欢猫女和..."

3."Batman喜欢猫女和阿福" should look like "Batman喜欢猫女和..."

I know Android has a property to do this, how about Swift?

Lookingforward for your response, and sorry for my poor English description.

Answer 1

You can iterate your string indices counting the characters, if it is a chinese character add 2 otherwise add 1. If the count is equal to 16 return the substring up to the current index with "…" at the end. Something like:

extension Character {
    var isChinese: Bool {
        String(self).range(of: "\\p{Han}", options: .regularExpression) != nil
    }
}

---

extension StringProtocol {
    var limitedLenghtLabelText: String {
        var count = 0
        for index in indices {
            count += self[index].isChinese ? 2 : 1
            if count == 16 {
                let upperBound = self.index(after: index)
                return String(self[..<upperBound]) + (upperBound < endIndex ? "…" : "") }
        }
        return String(self)
    }
}

---

"蝙蝠侠喜欢猫女和阿福".limitedLenghtLabelText   // "蝙蝠侠喜欢猫女和…"

"Batman喜欢猫女和阿福".limitedLenghtLabelText  // "Batman喜欢猫女和…"