Accessing Dictionaries inside a Dictionary by Index in Obj-C - objective-c

Question

I'm currently trying to learn Objective-C and I've stumbled across a little problem.
I want to build an iPad Application for collecting simple Numbers,which the User enters, by Date and Time.
To do that I thought of this Structure:
Dictionary("main")
Dictionary("27012013") //this holds all data for the 27th of January 2013
Index = 0
3:33pm = 123 //this would mean at 3:33pm there was a value of 123
..other values to follow
Dictionary("28012013") //and so on
So basically there is one big Dictionary called "main" which holds the dictionaries for all days which then hold their index and all recorded values.
I get the Value's by a UIAlertView Input which then calls the
(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
delegate method in which then the current time and date is saved in NSString's like this:
NSDateFormatter *format = [[NSDateFormatter alloc] init];
[format setDateStyle:NSDateFormatterNoStyle];
[format setTimeStyle:NSDateFormatterShortStyle];
NSString *time = [format stringFromDate:[NSDate date]];
NSLog(#"Time: %# and entered Text:%#",time,returnvalue.text);
//Which Date do we have
[format setDateStyle:NSDateFormatterShortStyle];
[format setTimeStyle:NSDateFormatterNoStyle];
NSString *date = [format stringFromDate:NSDate.date];
NSLog(#"Found Date:%#",date);
NSString *identifier =
[[date componentsSeparatedByCharactersInSet:
[NSCharacterSet punctuationCharacterSet]] componentsJoinedByString:#""];
NSLog(#"Identifier:%#",identifier);
where returnvalue.text holds the entered text. I then check if the dictionary called like the NSString identifier already exist and if not add it to main:
if([main objectForKey:identifier] == nil){
//No Dict Available for current Date so create one:
//there should be no more than 30 Entries per Day
NSMutableDictionary *d = [[NSMutableDictionary alloc] initWithCapacity:30];
[d setObject:identifier forKey:#"Name"];
NSNumber* tmpi = [NSNumber numberWithInteger:main.count];
[d setObject:tmpi forKey:#"Index"];
//and store the recieved value in it
[d setObject:returnvalue.text forKey:time];
[main setObject:d forKey:identifier];
}
else{
NSMutableDictionary *d = [main objectForKey:identifier];
[d setObject:returnvalue.text forKey:time];
}
The First question here is: Do I have to use main.count or main.count+1?
Furthermore I want to display they information in tableView in which each day should have his own section. For the method
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
I therefore need to address they dictionaries inside the main dictionary by Index or e.g. filter them by their Index key to return the number of values inside of them.
I do now I could use a giant NSArray for main but this would make the method for determining if the dictionary for the day already exist more complicated and would rather not want to do this.
So could anyone please help me?
Thanks in Advance

Answer 1

First Answer:
it depends on you but "main.count" will return the number of objects in dictionary may be it's zero. So if you want to start from zero then it's good otherwise +1.
Second Answer:
here is function of NSDictionary "allKeys" which return all the keys as "NSArray" then you can get each key by index if you don't know about the "key" just get it using index from array.