1.第一種方式直接採用拼接方式，例：

-(NSString *)convertToJsonStr
{
 int random=arc4random_uniform(100000);
 NSString *nonce = [NSString stringWithFormat:@"%d",random];
 NSString *sign = [NSString stringWithFormat:@"%@%@%@%@%lld",[self getToken],[self getArea],nonce,[self getClient],[KQDateJS httpTimeCut]];
//拼接json字串、
NSString
 
 *signInfo = [NSString stringWithFormat:@"{\"Token\":\"%@\",\"Area\":\"%@\",\"Nonce\":\"%d\",\"Time\":\"%lld\",\"Client\":\"%@\",\"Sign\":\"%@\"}",[self getToken],[self getArea],random,[KQDateJS httpTimeCut],[self getClient],sign];
    return signInfo;
}

2.第二種採用NSJSONSerialization提供的方法json轉json字串

-(NSString
 
 *)convertToJsonData:(NSDictionary *)dict
{
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&error];
    NSString *jsonString;
    if (!jsonData) {
        NSLog(@"%@",error);
    }else{
        jsonString = [[NSString
 
 alloc]initWithData:jsonData encoding:NSUTF8StringEncoding];
    }
    NSMutableString *mutStr = [NSMutableString stringWithString:jsonString];
    NSRange range = {0,jsonString.length};
    //去掉字串中的空格
    [mutStr replaceOccurrencesOfString:@" " withString:@"" options:NSLiteralSearch range:range];
    NSRange range2 = {0,mutStr.length};
    //去掉字串中的換行符
    [mutStr replaceOccurrencesOfString:@"\n" withString:@"" options:NSLiteralSearch range:range2];
    return mutStr;

}

通過以上2種方法轉的json字串是不帶空格和換行符的。