Question

I have an expense tracking iOS Application using Core Data Model:

Scenario:

-> An abstract parent entity named “Money” with attributes “vendor”, “date”, “amount” and so on. The two sub-entities “Expense” and “Income” inherit from the parent entity “Money”. Then there are other entities such as “Category” and “subCategory” with their attributes. Total as of now: 5 entities (Money, Expense, Income, Category and Subcategory) in my data model.

Question: What I want to achieve is to track expenses daily, per week, bi-weekly, monthly and yearly. I am thinking to make an entity say “Months” with 12 attributes ( Jan – Dec – > month names) but isn’t that too much complicated?

Thoughts?

I have a Table-view and using NSFetchedResultsController to fill my table-view with the mix od expenses and Incomes.

Answer 1

You have to create an NSFetchRequest with an NSPredicate that filters for the appropriate time period. Let’s say you want to list all expenses between two dates your could implement a method that returns an NSFetchRequest that filters for this period:

- (NSFetchRequest *)filteredFetchRequestForEntity:(NSString *)entityName startDate:(NSDate *)startDate endDate:(NSDate *)endDate
{
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@", startDate, endDate];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:entityName inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];
    [fetchRequest setPredicate:predicate];

    return fetchRequest;
}

You could then use this fetchRequest for example in an NSFetchedResultsController
similar to my answer in your other question:
CoreData and TableViews

Then all you’d have to do is create the NSDate objects for start- and endDate for your desired time period and pass them to this method.