SlicePhotos.m

	- (NSArray<PhotoSection *> *)fetchGroupedPhotos {
	    NSArray<LocalPhoto *> *photos = [self fetchPhotos];
	
	    NSMutableArray<PhotoSection *> *sections = [NSMutableArray new];
	
	    NSMutableArray<LocalPhoto *> *photosForCurrentSection = [NSMutableArray new];
	    for (LocalPhoto *photo in photos) {
	        if (photosForCurrentSection.count == 0) {
	            [photosForCurrentSection addObject:photo];
	            continue;
	        }
	
	        if ([photosForCurrentSection.lastObject.date timeIntervalSinceDate:photo.date] > 60*60) {
	            PhotoSection *section = [[PhotoSection alloc] init];
	            section.header = [self.dateFormatter stringFromDate:photosForCurrentSection.firstObject.date];
	            section.photos = photosForCurrentSection;
	            [sections addObject:section];
	            photosForCurrentSection = [NSMutableArray new];
	            [photosForCurrentSection addObject:photo];
	        } else {
	            [photosForCurrentSection addObject:photo];
	        }
	    }
	    if (photosForCurrentSection.count != 0) {
	        PhotoSection *section = [[PhotoSection alloc] init];
	        section.header = [self.dateFormatter stringFromDate:photosForCurrentSection.firstObject.date];
	        section.photos = photosForCurrentSection;
	        [sections addObject:section];
	    }
	    return sections;
	}