iOS Unicode编码/解码

//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;
    
}