How to limit UILabel's max characters-CodePudding

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.

CodePudding user response：

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…"