2022-11-01 增加Swift版

  public extension String {
    
    /// 编码类型
    enum Encode {
        case unicode
    }
    
    /// 字符串编码
    /// - Parameter using: 编码类型
    func encode(_ using: Encode) -> String? {
        switch using {
            case .unicode: return utf16.map({ String(format:"\\U%04x", $0) }).joined()
        }
        return nil
    }

    /// 字符串解码
    /// - Parameter using: 编码类型
    func decode(_ using: Encode) -> String? {
        switch using {
            case .unicode:
                let text = "\"" + replacingOccurrences(of: "\\u", with: "\\U") + "\""
                if let date = text.data(using: .utf8) {
                    do {
                        let result = try PropertyListSerialization.propertyList(
                            from: date,
                            options: .mutableContainers,
                            format: nil
                        )
                        return result as? String
                    } catch {
                        print(error)
                    }
                }
        }
        return nil
    }

  }

//编码 （该方法编码了所有内容，包括字母和数字）
- (NSString *)encodeUnicode {
    
    if (MONull(self)) {
        return nil;
    }
    
    NSMutableString *string = [[NSMutableString alloc] init];
    
    for (int i = 0; i < self.length; i++) {

        unichar _char = [self characterAtIndex:i];

        //不足4为左边补0，避免解码错误
        NSString *str = [NSString stringWithFormat:@"%04x", _char];
        
        [string appendFormat:@"\\u%@", str];
    }
    
    return string;
}

//解码
- (NSString *)decodeUnicode {
    
    if (MONull(self)) {
        return nil;
    }
    
    const char *charString = self.UTF8String;
    
    NSData *data = [NSData dataWithBytes:charString length:strlen(charString)];
    
    NSString *string = [[NSString alloc] initWithData:data encoding:NSNonLossyASCIIStringEncoding];
    
    return string;
    
}