display the returned values in section header - objective-c

Question

i am working on an expense tracker kind of application.i am able to store and retrieve sorted data perfectly using coredata.
i am storing date.i am able to retrieve date in a sorted order.but i want to the date in the section header and related data in that table.
ex:
Dec 31st 2011 ---------> Section Header
xxxxxxx yyyyyy ----->cell with labels
Jan 1st 2012---------->Section Header
xxxxxxx yyyyyy ------>cell with labels.
i am able to receive the dates in a sorted order.but how to display them in a section header in a sorted order and how to declare the number of sections in tableView-noOfSections method?
//Code i used for retrieving data.
- (void)viewDidLoad
{
AppDelegate *appDelegate = [[UIApplication sharedApplication]delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:#"NewExpense" inManagedObjectContext:context];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc]init];
NSSortDescriptor *date = [[NSSortDescriptor alloc]initWithKey:#"date" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc]initWithObjects:date,nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[fetchRequest setEntity:entityDesc];
NSError *error;
self.listOfExpenses = [[context executeFetchRequest:fetchRequest error:&error]retain] [fetchRequest release];
[super viewDidLoad];
}
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;// as of now i have taken one.
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
[self.listOfExpenses count]; 
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//labels are created and added to the cell's subview.
NSManagedObject *records = nil;
records = [self.listOfExpenses objectAtIndex:indexPath.row];
self.firstLabel.text = [records valueForKey:#"category"];
NSString *dateString = [NSString stringWithFormat:#"%#",[records valueForKey:#"date"]];
NSString *dateWithInitialFormat = dateString;
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
[dateFormatter setDateFormat:#"yyyy-MM-dd HH:mm:ss Z"];
NSDate *date = [dateFormatter dateFromString:dateWithInitialFormat];
[dateFormatter setDateFormat:#"dd-MM-yyyy"];
NSString *dateWithNewFormat = [dateFormatter stringFromDate:date];
self.secondLabel.text = dateWithNewFormat;
NSString *amountString = [NSString stringWithFormat:#"%#",[records valueForKey:#"amount"]];
self.thirdLabel.text = amountString;
totalAmount = totalAmount + [amountString doubleValue];
}

Answer 1

Date in the section header is a bit tricky, but there is very good sample code from Apple out there which I am using in one of my current apps successfully. Look at DateSectionTitles.
In short, you need to use a NSFetchedResultsController and define the sectionNameKeyPath with a separate property of your entity (the date itself won't do because it is accurate to the second). In numberOfSections you will have to return whatever the fetched results controller gives you, not 1 as above. numberOfRowsInSection will have to be adjusted as well, you get the idea.
Apple calculates a primitive date and reconstructs it when it has to format the string for the section header. All pretty straight forward. Just follow the sample code and you have solved this in no time.

Answer 2

You can use NSSortDescriptor:
NSFetchRequest *request = [[NSFetchRequest alloc] init];
...
NSSortDescriptor * sort = [[NSSortDescriptor alloc] initWithKey:sortingKey ascending:ascending];
NSArray * sortDescriptors = [NSArray arrayWithObject: sort];
[request setSortDescriptors:sortDescriptors];
as sortingKey you will pass in your case date.
See docs on NSSortDecsriptor here:
https://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSSortDescriptor_Class/Reference/Reference.html