iOS How do I retrieve managed objects whose dates fall within one week of a given date?

[moonman239]

Example scenario: I have multiple employees in a database. This database has information on when each employee joined a given department. The end user wants to know how many people have joined the department in the past 7 days.

I wouldn't want the app to fetch all of the employee records, then comb through every record looking for records of employees who joined in the past 7 days.

 

[waterskier2007]

What kind of database (basic SQLite, Core Data, etc)? Is it local on the iOS device?

 

[moonman239]

What kind of database (basic SQLite, Core Data, etc)? Is it local on the iOS device?

SQLite. I found an answer online, thanks to Google and to a helpful person at StackOverflow.

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDate *startOfWeek;
    NSTimeInterval timeInterval;
    [calendar rangeOfUnit:NSWeekCalendarUnit startDate:&startOfWeek interval:&timeInterval forDate:[NSDate date]];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >=%@)",startOfWeek];
// Execute a fetch request with [I]predicate[/I] set as a predicate.

 

[moonman239]

[__NSCFNumber timeIntervalSinceReferenceDate]: unrecognized selector sent to instance

I can't figure out why my code would give me this error. Below are the relevant lines of code.

NSDate *date = [NSDate date];
double timestamp = [date timeIntervalSince1970];

EDIT: After reading this Webpage, I found that the problem lies in the code for the predicate I created so that the app would fetch the managed object that corresponds to the given date. Instead of telling it to compare an NSDate object to date, I compared it to timestamp.

 

[ArtOfWarfare]

I can't figure out why my code would give me this error. Below are the relevant lines of code.

NSDate *date = [NSDate date];
double timestamp = [date timeIntervalSince1970];

EDIT: After reading this Webpage, I found that the problem lies in the code for the predicate I created so that the app would fetch the managed object that corresponds to the given date. Instead of telling it to compare an NSDate object to date, I compared it to timestamp.

What? There's no predicate in the two lines of code you showed us...

 

[moonman239]

Core Data model seems to have no managed objects that meet date predicate.

My app has a database. In the database's entity is a date attribute. In one of my view controllers, the app is supposed to fetch managed objects whose dates fall on the same week as the current date. I have determined that the predicate is the only problem. Its code is below this paragraph.

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >=%@)",startOfWeek];

EDIT: startOfWeek is an NSDate object that is set to the correct value.