How could this be possible? UITableView datasource Count Weird Behavior - ios

Question

I don't understand how this is possible or why this is happening. Can anyone give me an idea?
I added more code to help you figure it out, however, i'm not sure how the extra code will help.
NSMutableArray *messages = [[NSMutableArray alloc] init];
PFUser *currentUser = [PFUser currentUser];
PFQuery *query = [PFQuery queryWithClassName:#"message"];
[query whereKey:#"receiver" equalTo:currentUser.objectId];
[query orderByDescending:#"createdAt"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (!error && objects !=NULL) {
NSMutableArray *listOfLastMsgs = [[NSMutableArray alloc] init];
for (PFObject *object in objects) {
Boolean *tester = false;
for(int i = 0;i<listOfLastMsgs.count;i++){
if([[object objectForKey:#"sender"] isEqualToString:[[listOfLastMsgs objectAtIndex:i] objectForKey:#"sender"]]){
tester = true;
}
}
if(!tester){
[listOfLastMsgs addObject:object];
}
}
for(int i = 0;i<listOfLastMsgs.count;i++){
NSString *s = [[listOfLastMsgs objectAtIndex:i] objectForKey:#"message"];
if(s.length > 80){
s = [s substringToIndex:80];
}
[messages addObject:s];
}
NSLog(#"in did load %lu", (unsigned long)messages.count);
[self.tableView reloadData];
} else {
// Log details of the failure
NSLog(#"Error: %# %#", error, [error userInfo]);
}
}];
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
NSLog(#"in number of rows %lu", (unsigned long)messages.count);
return messages.count;
}
Here is my output log
2014-07-25 18:15:32.980 myapp[5696:60b] in number of rows 0
2014-07-25 18:15:35.990 myapp[5696:60b] in did load 2
2014-07-25 18:15:35.991 myapp[5696:60b] in number of rows 0

Answer 1

Assuming that big hunk of code is in your viewDidLoad the problem is simple - you have a local messages variable that you setup in viewDidLoad and your numberOfRowsInSection is referencing an uninitialized messages instance variable.
Assuming you really do have an ivar named messages, in viewDidLoad, change:
NSMutableArray *messages = [[NSMutableArray alloc] init];
to:
messages = [[NSMutableArray alloc] init];