void mutbaleString(){

    NSMutableString *str=[NSMutableStringstringWithFormat:@"cooljune"];

    [strappendString:@"bianbian"];

    [str appendFormat:@"bianbian no is %i",10];

   NSString *str2=@"sss";

//把str2 copy一份然后再加上添加的字符串变成一个新的对象，str2并为发生改变

    NSString *str3=[str2stringByAppendingString:@"kkkkk"];

    NSLog(@"拼接之后的字符串是：%@",str);

}

void stringAppend(){

   NSString *qq=@"123456";

   NSString *no=@"123456";

    NSMutableString *str=[NSMutableStringstringWithFormat:@"http://qq.com?"];

    [strappendFormat:@"qq=%@",qq];    

    [strappendFormat:@"&pwd=%@",no];   

    NSLog(@"nsstring=%@",str);

}

void stringDelete(){

    NSMutableString *s=[NSMutableStringstringWithFormat:@"http://baidu.com/com"];

    //NSRange range=[s rangeOfString:@".com"];

    //从后往前搜索

    NSRange range=[srangeOfString:@"com"options:NSBackwardsSearch];

    [s deleteCharactersInRange:range];

    NSLog(@"after delete value:%@",s);

}

//字符串替换

void replace(){

    NSMutableString *st=[NSMutableStringstringWithFormat:@"baidu.com/app"];

   NSRange range=[st rangeOfString:@"app"];

    //[st replaceCharactersInRange:range withString:@"apk"];

    [stinsertString:@"/web"atIndex:range.location+range.length];

    NSLog(@"st---->%@",st);

}