How to create titleForHeaderInSection based on an object value - ios

Question

I have an object (core data object) that this object have a property called "weeks" to define how many weeks ago this object was created.
Now im displaying this type of objects in a table view, and I created this table view as grouped table view and now I want to set the headers of the grouped table view by the number of weeks.
So
header:2 weeks ago
obj1
obj2
heaser:3 weeks ago
obj3
obj4
obj5
So I guess the magic happened in:
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
//Settings up the sections title
if(section == 0) {
return #"something";
} else {
return #"something";
}
}
So now I have this object called Target, and its weeks property (target.weeks).
How can i use it to set the headers grouped by number of weeks of the object?
thanksss

Answer 1

Since you are dealing with core data the best solution is to use NSFetchedResultsController. Apple has provided this class specifically for fetching core data objects and displaying them on table view and you can even mention the attribute based on which you wish to categorise your objects into sections.
In a non core data scenario one way is to create an NSDictionary with one entry for each section. Nothing stops you from using this technique for core data objects. But NSFetchedResultsController is much better. The key will be the section title and value will be an NSArray of objects that you wish to show in that section.
Your dictionary will look like {sec1:[row0Obj,row1obj], sec2:[row0Obj, row1Obj]}
NSDictionary *dataSourceDictionary; //Add data to this dictionary as explained above
- (NSDictionary *)entryForSection:(NSInteger)section {
NSArray *allSections = [dataSourceDictionary allKeys];
//sort the sections array here to make sure your setions appear in correct order
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:#"self" ascending:YES];
allSections = [allSections sortedArrayUsingDescriptors:#[sortDescriptor]];
NSString *sectionTitle = allSections[section];
NSArray *objectsInSection = dataSourceDictionary[sectionTitle];
return #{ sectionTitle : objectsInSection };
}
- (NSArray *)objectsForSection:(NSInteger)section {
NSDictionary *entry = [self entryForSection:section];
NSArray *objects = (NSArray *)entry.allValues.firstObject;
return objects;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return dataSourceDictionary.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self objectsForSection:section].count;
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
NSDictionary *entry = [self entryForSection:section];
NSString *title = entry.allKeys.firstObject;
return title;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSArray *objectsForSection = [self objectsForSection:indexPath.section];
id objectForRow = objectsForSection[indexPath.row];
//Configure your cell using objectForRow
//[cell configureWithObject:object];
//return cell;
}