Example how to build a class for iwascoding's Objective-C ORM system

GSSavedAttributeSet.m

// GSSavedAttributeSet.h

#import "SDBObject.h"
#import <SDBSynch/SDBSynchProtocols.h>

NS_ASSUME_NONNULL_BEGIN

@class GSEbayItemSpecific;

/** A named set of pre-filled listing attributes, which is specific to a certain eBay site and possibly categories */
@interface GSSavedAttributeSet : SDBObject <SDBSynchContainer>

- (instancetype) initWithContext:(SDBContext*) inContext
                            name:(NSString*) inName
                      attributes:(NSArray<GSEbayItemSpecific*>*) inAttributes
                          siteID:(NSInteger) inSiteID
               primaryCategoryID:(NSInteger) inPrimaryCategoryID
             secondaryCategoryID:(NSInteger) inSecondaryCategoryID;

@property (readonly) NSString* name;
@property (readonly) NSArray<GSEbayItemSpecific*>* attributes;
@property (readonly) NSInteger siteID;
@property (readonly) NSInteger primaryCategoryID;
@property (readonly) NSInteger secondaryCategoryID;

@end

NS_ASSUME_NONNULL_END


// GSSavedAttributeSet.m

#import "GSSavedAttributeSet.h"
#import <IHLevelDB/SDBContext+Fetching.h>

@implementation GSSavedAttributeSet

/** Retrieve all attribute sets specific to certain eBay site, ordered by their name. */
+ (NSArray<GSSavedAttributeSet*>*) savedAttributeSetsForSiteID:(NSInteger) inSiteID inContext:(SDBContext*) inContext
{
    return [inContext fetchObjectsOfClass:GSSavedAttributeSet.class
                        matchingPredicate:[NSPredicate predicateWithFormat:@"inSiteID == %ld", inSiteID]
                       sortedByDescriptor:[NSSortDescriptor sortDescriptorWithKey:@"name"
                                                                        ascending:NO]];
}

/** Retrieve all attribute sets specific to certain eBay site, ordered by their name. */
+ (GSSavedAttributeSet*) savedAttributeSetWithName:(NSString*) inName siteID:(NSInteger) inSiteID inContext:(SDBContext*) inContext
{
    return [[inContext fetchObjectsOfClass:GSSavedAttributeSet.class
                         matchingPredicate:[NSPredicate predicateWithFormat:@"name == %@ && inSiteID == %ld", inName, inSiteID]]
            anyObject];
}

/** Index keys for this class for faster fetching */
+ (NSSet*) propertyNamesToIndex
{
    return [NSSet setWithObjects:@"name", @"siteID", nil];
}

/** Prevent instance from being automatically deleted from database when they aren't referenced by any other object. */
+ (BOOL) instancesShouldAutoDelete
{
    return NO;
}

- (instancetype) initWithContext:(SDBContext*) inContext
                            name:(NSString*) inName
                      attributes:(NSArray<GSEbayItemSpecific*>*) inAttributes
                          siteID:(NSInteger) inSiteID
                pimaryCategoryID:(NSInteger) inPrimaryCategoryID
             secondaryCategoryID:(NSInteger) inSecondaryCategoryID
{
    self = [super initWithContext:inContext];
    if (self) {
        _name = inName;
        _attributes = inAttributes;
        _siteID = inSiteID;
        _primaryCategoryID = inPrimaryCategoryID;
        _secondaryCategoryID = inSecondaryCategoryID;
    }
    return self;
}
@end