NSMutableString*str=[[NSMutableStringalloc]init];[strappendString:@"111"];//追加字符串[strappendFormat:@"%c",'ABC'];//追加字符串[strinsertString:@"mx"atIndex:4];//插入字符串,从第几个开始插入[strinsertString:[NSStringstringWithFormat:@"%d",25]atIndex:4];/插入字符串,从第几个开始插入[strdeleteCharactersInRange:NSMakeRange(3,5)];//从第三个字符串开始删除5个字符[strreplaceCharactersInRange:NSMakeRange(3,2)withString:@"mingxun"];//修改