Tag Archives: initialization

NSMutableArray count always returns zero

Posted by on March 6, 2011 No comments

The code is as follows, rowsToUpdate is NSMutableArray *, [sites count] is greater than 0, and there is value for row index, but [rowsToUpdate count] always returns 0:

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for (int i=0; i<[sites count]; i++) {
    NSLog(@"row index: %i, %@", i, [NSString stringWithFormat:@"%i", i]);
    [rowsToUpdate addObject:[NSString stringWithFormat:@"%i", i]];
    NSLog(@"[rowsToUpdate count] = %i", [rowsToUpdate count]);
}

There is no obvious problem with the code, and it doesn’t make sense to return 0.

After a couple of search, I found it on stackoverflow.com that I missed the initialization for “rowsToUpdate”. The fix is as follows (a couple lines of code added):

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if (rowsToUpdate == nil) {
    rowsToUpdate = [[NSMutableArray alloc] init];
}
else {
    [rowsToUpdate removeAllObjects];
}
 
for (int i=0; i<[sites count]; i++) {
    NSLog(@"row index: %i, %@", i, [NSString stringWithFormat:@"%i", i]);
    [rowsToUpdate addObject:[NSString stringWithFormat:@"%i", i]];
    NSLog(@"[rowsToUpdate count] = %i", [rowsToUpdate count]);
}