[Swift]将字符串拆分为N份

比如常见需求：将字符串等分100份 / 将字符串拆分为字符串数组打乱顺序后加密存储

    /// 字符串拆分为字符串数组
    ///
    /// - Parameters:
    ///   - str: 被拆分字符串
    ///   - count: 拆分为多少段
    private func stringSplitArr(string: String, count: Int) -> [String] {
        let originalString = string
        let subStringLength = originalString.count / count
        var startIndex = originalString.startIndex
        var endIndex = originalString.index(startIndex, offsetBy: subStringLength)
        var subStrings = [String]()

        for i in 1...count {
            let subString = String(originalString[startIndex..<endIndex])
            subStrings.append(subString)
            startIndex = endIndex
            if i + 1 == count { // 最后一次截取剩余所有
                endIndex = originalString.endIndex
            } else {
                endIndex = originalString.index(endIndex, offsetBy: subStringLength, limitedBy: originalString.endIndex) ?? originalString.endIndex
            }
        }

        return subStrings
    }