ios - 如何知道两个表情符号是否会显示为一个表情符号？

Question

表情符号 👍🏼 由 2 个 unicodeScalars 👍 U+1F44D、🏼 U+1F3FC 组成。

如何将其识别为 1 个“已显示”的表情符号，因为它将在 iOS 上如此显示？

Answer 1

Swift 4 (Xcode 9) 更新

从 Swift 4 开始，“表情符号序列”被视为单个字素集群(根据 Unicode 9 标准):

let s = "a👍🏼b👨‍❤️‍💋‍👨"
print(s.count) // 4

因此不再需要其他解决方法。

---

(Swift 3 及更早版本的旧答案:)

一个可能的选择是枚举和计算字符串中的“组合字符序列”:

let s = "a👍🏼b👨‍❤️‍💋‍👨"
var count = 0
s.enumerateSubstringsInRange(s.startIndex..<s.endIndex,
                             options: .ByComposedCharacterSequences) {
                                (char, _, _, _) in
                                if let char = char {
                                    count += 1
                                }
}
print(count) // 4

另一种选择是查找组合字符的范围给定索引处的序列:

let s = "👨‍❤️‍💋‍👨"
if s.rangeOfComposedCharacterSequenceAtIndex(s.startIndex) == s.characters.indices {
    print("This is a single composed character")
}

作为 String 扩展方法:

// Swift 2.2:
extension String {
    var composedCharacterCount: Int {
        var count = 0
        enumerateSubstringsInRange(characters.indices, options: .ByComposedCharacterSequences) {
            (_, _, _, _) in count += 1
        }
        return count
    }

    var isSingleComposedCharacter: Bool {
        return rangeOfComposedCharacterSequenceAtIndex(startIndex) == characters.indices
    }
}

// Swift 3:
extension String {
    var composedCharacterCount: Int {
        var count = 0
        enumerateSubstrings(in: startIndex..<endIndex, options: .byComposedCharacterSequences) {
            (_, _, _, _) in count += 1
        }
        return count
    }

    var isSingleComposedCharacter: Bool {
        return rangeOfComposedCharacterSequence(at: startIndex) == startIndex..<endIndex
    }
}

例子:

"👍🏼".composedCharacterCount // 1
"👍🏼".characters.count       // 2

"👨‍❤️‍💋‍👨".composedCharacterCount // 1
"👨‍❤️‍💋‍👨".characters.count       // 4

"🇩🇪🇨🇦".composedCharacterCount // 2
"🇩🇪🇨🇦".characters.count       // 1

如您所见，Swift 字符(扩展字素簇)的数量可以或少于组成字符序列的数量。