Question

Can anyone please help me out.I have been stuck with this NSMutableArray for last 2-3 days. I am beginner in Objective-C and I don’t know what is the error in the code.In my program, I have created a sqlite database.It contain 3 fields and i have successfully inserted the values into db.And I am extracting these values from the db into NSMutableArray and displaying this array.But the problem is only last element is displaying and not whole data. I dont understand why it is displaying only the last element.I will paste the code below- Can anyone please check it and help me out.

- (void)viewDidLoad
{

   NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
   NSString *documentsDir = [documentPaths objectAtIndex:0];

   databasePath = [documentsDir stringByAppendingPathComponent:@"TDL1.db"];

   const char *dbpath = [databasePath UTF8String];

   sqlite3_stmt    *statement;

        if (sqlite3_open(dbpath, &TDLDB) == SQLITE_OK)
         {
                    NSString *querySQL = [NSString stringWithFormat: @"SELECT MYTASK, SUBTASK FROM TDL1 "];

                    const char *query_stmt = [querySQL UTF8String];



      if (sqlite3_prepare_v2(TDLDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)

       {
            while (sqlite3_step(statement) == SQLITE_ROW)
              {
                     todolist2=[[NSMutableArray alloc]init];

                      NSString *mytask = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 0)];

                      NSString *subtask = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 1)];

                   todolist2 = [NSMutableArray arrayWithObjects:mytask,subtask, nil];

                       NSLog(@"THE array is:%@",todolist2);

       } 

                sqlite3_finalize(statement);
}
              sqlite3_close(TDLDB);

}
         NSLog(@"THE outside array is:%@",todolist2);
[super viewDidLoad];

}

And in the console I am getting the following output :-

2012-09-06 11:33:23.529 TDL[823:f803] THE array is:(
    task0,
    task0
)
2012-09-06 11:33:23.532 TDL[823:f803] THE array is:(
    task1,
    task1
)
2012-09-06 11:33:23.533 TDL[823:f803] THE array is:(
    task2,
    task2
)
2012-09-06 11:33:23.534 TDL[823:f803] THE array is:(
    task3,
    task3
)
2012-09-06 11:33:23.534 TDL[823:f803] THE array is:(
    task4,
    task4
)
2012-09-06 11:33:23.535 TDL[823:f803] THE array is:(
    task5,
    task5
)
2012-09-06 11:33:23.536 TDL[823:f803] THE array is:(
   task6,
   task6
)
2012-09-06 11:33:23.537 TDL[823:f803] THE array is:(
    task6,
    task6
)
2012-09-06 11:33:23.537 TDL[823:f803] THE array is:(
    task7,
    task7
)
2012-09-06 11:33:23.538 TDL[823:f803] THE array is:(
    task7,
    task7
)
2012-09-06 11:33:23.539 TDL[823:f803] THE array is:(
    task8,
    task8
)
2012-09-06 11:33:23.539 TDL[823:f803] THE array is:(
    task9,
    task9
)
2012-09-06 11:33:23.540 TDL[823:f803] THE array is:(
   task10,
   task10
)
2012-09-06 11:33:23.540 TDL[823:f803] THE outside array is:(
   task10,
   task10
)
2012-09-06 11:33:23.541 TDL[823:f803] could not prepare statement: not an error

I want to display the values starting from task0 to task10.How to show that?Please tell me the solution.Thanks in advance.

Answer 1

You are just making a new NSMutableArray each time you go through your while (sqlite3_step(statement) == SQLITE_ROW) loop. Actually you are making one twice. Move the following line outside the while loop:

todolist2=[[NSMutableArray alloc]init];

Then inside your while loop instead of recreating a new array each time with:

todolist2 = [NSMutableArray arrayWithObjects:mytask,subtask, nil];

Instead use:

[todolist2 addObject:myTask];
[todolist addObject:subTask];

These lines will add the two strings to the end of your array.