将UNicode编码转化为UTF－8

- (NSString *)replaceUnicode:(NSString *)unicodeStr
{
    NSString *tempStr1 = [unicodeStr stringByReplacingOccurrencesOfString:@"\\u"withString:@"\\U"];
    NSString *tempStr2 = [tempStr1 stringByReplacingOccurrencesOfString:@"\""withString:@"\\\""];
    NSString *tempStr3 = [[@"\""stringByAppendingString:tempStr2] stringByAppendingString:@"\""];
    NSData *tempData = [tempStr3 dataUsingEncoding:NSUTF8StringEncoding];
    NSString *returnStr = [NSPropertyListSerialization propertyListFromData:tempData
                                                           mutabilityOption:NSPropertyListImmutable
                                                                     format:NULL
                                                           errorDescription:NULL];
    return [returnStr stringByReplacingOccurrencesOfString:@"\\r\\n"withString:@"\n"];
}