NSManagedObject's #synthesize attribute stays faulted after modifying a relationship - core-data

Question

I'm using code derived from Apple's DateSectionTitles example code. In my class Appointment I have a relationship to Location. Furthermore I generate a section identifier used by a UITableViewController.
#class Location;
#interface Appointment : NSManagedObject
#property (nonatomic, retain) NSDate * begin;
#property (nonatomic, retain) NSDate * end;
#property (nonatomic, retain) Location * location;
#property (nonatomic, retain) NSString *sectionIdentifier;
#property (nonatomic, retain) NSString *primitiveSectionIdentifier;
#end
#implementation Appointment
#synthesize begin = _begin;
#dynamic end;
#dynamic location;
#dynamic primitiveSectionIdentifier;
#dynamic sectionIdentifier;
#pragma mark -
#pragma mark Transient properties
- (NSString *)sectionIdentifier {
// Create and cache the section identifier on demand.
[self willAccessValueForKey:#"sectionIdentifier"];
NSString *tmp = [self primitiveSectionIdentifier];
[self didAccessValueForKey:#"sectionIdentifier"];
if (!tmp) {
/*
Sections are organized by month and year. Create the section identifier as a string representing the number (year * 1000) + month; this way they will be correctly ordered chronologically regardless of the actual name of the month.
*/
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
fromDate:[self begin]];
tmp = [NSString stringWithFormat:#"%d", ([components year] * 10000) + [components month] * 100 + [components day]];
[self setPrimitiveSectionIdentifier:tmp];
}
return tmp;
}
#pragma mark -
#pragma mark Begin setter
- (void)setBegin:(NSDate *)begin
{
// If the time stamp changes, the section identifier become invalid.
[self willChangeValueForKey:#"begin"];
[self willChangeValueForKey:#"primitiveSectionIdentifier"];
_begin = begin;
[self setPrimitiveSectionIdentifier:nil];
[self didChangeValueForKey:#"begin"];
[self didChangeValueForKey:#"primitiveSectionIdentifier"];
}
#end
The problem: After altering the location the data stays faulted.
Before modifying location the object looks like this:
<Appointment: 0x837d570> (entity: Appointment; id: 0x837c900 <x-coredata://83B2187C-00B3-4029-B4C5-4EB69C18FC59/Appointment/p1> ; data: {
begin = "2013-07-27 16:00:00 +0000";
end = "2013-07-27 18:00:00 +0000";
location = "0x837e6c0 <x-coredata://83B2187C-00B3-4029-B4C5-4EB69C18FC59/Location/p1>";
})
After altering the property location:
<Appointment: 0x9b7b1f0> (entity: Appointment; id: 0x9b7ab50 <x-coredata://83B2187C-00B3-4029-B4C5-4EB69C18FC59/Appointment/p1> ; data: <fault>)
If I relinquish from generating a section identifier and using a #dynamic instead of a #synthesized property it still works. What's the cause of this and how can I overcome this?

Answer 1

Thanks to Martin R who pointed me in the right direction I've found the problem in my code.
What I didn't know was the fact that Core Data automatically generates additional primitive properties for you:
For example, given an entity with an attribute firstName, Core Data
automatically generates firstName, setFirstName:, primitiveFirstName,
and setPrimitiveFirstName:. Core Data does this even for entities
represented by NSManagedObject. To suppress compiler warnings when you
invoke these methods, you should use the Objective-C 2.0 declared
properties feature, as described in “Declaration.”
(Source)
The fact that I wasn't aware of this leaded me to adopt the example code in a wrong way. The way it works for me is now:
#class Location;
#interface Appointment : NSManagedObject
#property (nonatomic, retain) NSDate * primitiveBegin;
#property (nonatomic, retain) NSDate * begin;
#property (nonatomic, retain) NSDate * end;
#property (nonatomic, retain) Location * location;
#property (nonatomic, retain) NSString *sectionIdentifier;
#property (nonatomic, retain) NSString *primitiveSectionIdentifier;
#end
#implementation Appointment
#dynamic primitiveBegin;
#dynamic begin;
#dynamic end;
#dynamic location;
#dynamic primitiveSectionIdentifier;
#dynamic sectionIdentifier;
#pragma mark -
#pragma mark Transient properties
- (NSString *)sectionIdentifier {
// Create and cache the section identifier on demand.
[self willAccessValueForKey:#"sectionIdentifier"];
NSString *tmp = [self primitiveSectionIdentifier];
[self didAccessValueForKey:#"sectionIdentifier"];
if (!tmp) {
/*
Sections are organized by month and year. Create the section identifier as a string representing the number (year * 1000) + month; this way they will be correctly ordered chronologically regardless of the actual name of the month.
*/
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
fromDate:[self begin]];
tmp = [NSString stringWithFormat:#"%d", ([components year] * 10000) + [components month] * 100 + [components day]];
[self setPrimitiveSectionIdentifier:tmp];
}
return tmp;
}
#pragma mark -
#pragma mark Begin setter
- (void)setBegin:(NSDate *)begin
{
// If the time stamp changes, the section identifier become invalid.
[self willChangeValueForKey:#"begin"];
[self setPrimitiveBegin:begin];
[self didChangeValueForKey:#"begin"];
[self setPrimitiveSectionIdentifier:nil];
}
#pragma mark -
#pragma mark Key path dependencies
+ (NSSet *)keyPathsForValuesAffectingSectionIdentifier
{
// If the value of timeStamp changes, the section identifier may change as well.
return [NSSet setWithObject:#"begin"];
}
#end