Chore.h

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@class Assignment;

@interface Chore : NSManagedObject

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSNumber * doMonday;
@property (nonatomic, retain) NSNumber * doSunday;
@property (nonatomic, retain) NSNumber * doWednesday;
@property (nonatomic, retain) NSNumber * coins;
@property (nonatomic, retain) NSNumber * doThursday;
@property (nonatomic, retain) NSNumber * difficulty;
@property (nonatomic, retain) NSNumber * doFriday;
@property (nonatomic, retain) NSString * instructions;
@property (nonatomic, retain) NSNumber * doTuesday;
@property (nonatomic, retain) NSNumber * doSaturday;
@property (nonatomic, retain) NSNumber * weekly;
@property (nonatomic, retain) NSDate * date;
@property (nonatomic, retain) NSNumber * weekNumber;
@property (nonatomic, retain) NSNumber * doThisWeek;
@property (nonatomic, retain) NSSet *assignment;

@property (readonly, copy) NSSet *players;
@property (nonatomic, retain) NSNumber * thisWeeks;


-(NSString*)days;
-(NSString*)daysNoCommas;
-(UIView*)complexityLabel;
@end

@interface Chore (CoreDataGeneratedAccessors)

- (void)addAssignmentObject:(Assignment *)value;
- (void)removeAssignmentObject:(Assignment *)value;
- (void)addAssignment:(NSSet *)values;
- (void)removeAssignment:(NSSet *)values;
@end

Chore.m

#import "Chore.h"
#import "Assignment.h"
#import "YRLabel.h"

@implementation Chore

@dynamic name;
@dynamic doMonday;
@dynamic doSunday;
@dynamic doWednesday;
@dynamic coins;
@dynamic doThursday;
@dynamic difficulty;
@dynamic doFriday;
@dynamic instructions;
@dynamic doTuesday;
@dynamic doSaturday;
@dynamic weekly;
@dynamic date;
@dynamic weekNumber;
@dynamic doThisWeek;
@dynamic assignment;
- (NSSet *)players {
    // use aggregate KVC to do the iteration automatically
    return [self.assignment valueForKey:@"player"]; 
}
-(NSNumber *) doThisWeek{
    if ([self.weekly boolValue]) {
        return [NSNumber numberWithBool:YES] ;
    }
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSWeekCalendarUnit;
    NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:[NSDate date]];
    NSUInteger week = [dateComponents week];
    if ([self.weekNumber intValue] % 2)
        if (week % 2) 
            return [NSNumber numberWithBool:YES] ;
    
    if (!week % 2) 
        if (![self.weekNumber intValue] % 2)
            return [NSNumber numberWithBool:YES] ;
    
    return [NSNumber numberWithBool:NO] ; 
}

-(NSString*)days{
    
    NSArray *daysMap = [NSArray arrayWithObjects:@"M", @"Tu", @"W", @"Th",@"F",@"Sa",@"Su",nil];
    //    NSMutableString *days = @"";
    NSSortDescriptor *alphaSort = [NSSortDescriptor sortDescriptorWithKey:@"day" ascending:YES];
    
    NSArray *children = [[self.assignment allObjects] sortedArrayUsingDescriptors:[NSArray arrayWithObject:alphaSort]];
    
    //    [self.assignment allObjects]
    NSMutableArray *allDays = [[NSMutableArray alloc] init];
    for (Assignment *ass in children) {
        [allDays addObject:ass.day];
    }
    
    NSMutableArray * unique = [NSMutableArray array];
    NSMutableSet * processed = [NSMutableSet set];
    
    for (NSNumber * number in allDays) {
        if ([processed containsObject:number] == NO) {
            [unique addObject:number];
            [processed addObject:number];
            NSLog(@"Sorted array %i", [number intValue]);
        }
    }
    NSMutableString *returnDays = [[NSMutableString alloc] init];
    for (NSNumber *thisDay in unique) {
        [returnDays appendFormat:@", %@", [daysMap objectAtIndex:[thisDay intValue]]];
        
    }
    
    NSRange range;
    range.location = 0;
    range.length = 1;
    if ([allDays count] > 0) {
        [returnDays deleteCharactersInRange:range];
        NSLog(@"Days %@", returnDays);
        
    }
    NSString *s = [[NSString alloc] initWithString:returnDays];
    
    [allDays release];
    [returnDays release];
    return [s autorelease];
    
}

-(NSString*)daysNoCommas{
    
    NSArray *daysMap = [NSArray arrayWithObjects:@"M", @"Tu", @"W", @"Th",@"F",@"Sa",@"Su",nil];
    //    NSMutableString *days = @"";
    NSSortDescriptor *alphaSort = [NSSortDescriptor sortDescriptorWithKey:@"day" ascending:YES];
    
    NSArray *children = [[self.assignment allObjects] sortedArrayUsingDescriptors:[NSArray arrayWithObject:alphaSort]];
    
    //    [self.assignment allObjects]
    NSMutableArray *allDays = [[NSMutableArray alloc] init];
    for (Assignment *ass in children) {
        [allDays addObject:ass.day];
    }
    
    NSMutableArray * unique = [NSMutableArray array];
    NSMutableSet * processed = [NSMutableSet set];
    
    for (NSNumber * number in allDays) {
        if ([processed containsObject:number] == NO) {
            [unique addObject:number];
            [processed addObject:number];
            NSLog(@"Sorted array %i", [number intValue]);
        }
    }
    NSMutableString *returnDays = [[NSMutableString alloc] init];
    for (NSNumber *thisDay in unique) {
        [returnDays appendFormat:@" %@", [daysMap objectAtIndex:[thisDay intValue]]];
        
    }
    
    NSRange range;
    range.location = 0;
    range.length = 1;
    
    NSString *s = [[NSString alloc] initWithString:returnDays];
    
    [allDays release];
    [returnDays release];
    return [s autorelease];
    
}
-(UIView*)complexityLabel{
    switch ([self.coins intValue]) {
        case 1:
            return [YRLabel choreLabel:@"EASY" :0 :@"07ba26" :12];
            break;
        case 3:
            return [YRLabel choreLabel:@"MEDIUM" :0 :@"e59d0a" :12];
            break;
        case 5:
            return [YRLabel choreLabel:@"HARD" :0 :@"c85957" :12];
            break;    
        default:
            return [YRLabel choreLabel:@"HARD" :0 :@"c85957" :12];
            break;
    }
    return nil;
}
@end

Predicate snippet.h

    NSPredicate *predicate = [NSPredicate predicateWithFormat:
                              @"player == %@ AND (day == %@ OR day == %@) AND chore.doThisWeek == YES", 
                              player, 
                              [NSNumber numberWithInt:[self todaysDayNumber]],
                              [NSNumber numberWithInt:[self yesterdaysDayNumber]]];