A.h

NS_ASSUME_NONNULL_BEGIN

@interface WObject : NSObject <NSCopying, NSSecureCoding>
+ (instancetype) objectWithJSONRepresentation:(NSDictionary *) JSONRepresentation;
+ (instancetype) objectWithJSONRepresentation:(NSDictionary *) JSONRepresentation excludingKeys:(NSArray *__nullable) keys;

+ (NSString *__nullable) replacementKeyForKey:(NSString *__nonnull) key;

+ (NSFormatter *__nullable) formatterForKey:(NSString *__nonnull) key;
+ (NSValueTransformer *__nullable) transformerForKey:(NSString *__nonnull) key;
@end

NS_ASSUME_NONNULL_END

A.m

#import "WObject.h"

#import <objc/runtime.h>

NS_ASSUME_NONNULL_BEGIN

@implementation WObject
+ (instancetype) objectWithJSONRepresentation:(NSDictionary *) JSONRepresentation {
	return [self objectWithJSONRepresentation:JSONRepresentation excludingKeys:nil];
}

+ (instancetype) objectWithJSONRepresentation:(NSDictionary *) JSONRepresentation excludingKeys:(NSArray *__nullable) excludingKeys {
	WObject *object = [[[self class] alloc] init];

	NSMutableDictionary *workingJSONRepresentation = [JSONRepresentation mutableCopy];
	for (id key in excludingKeys) {
		[workingJSONRepresentation removeObjectForKey:key];
	}

	[[workingJSONRepresentation copy] enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
		id actualKey = [self replacementKeyForKey:key];
		if (actualKey && ![actualKey isEqual:key]) {
			workingJSONRepresentation[actualKey] = workingJSONRepresentation[key];
			[workingJSONRepresentation removeObjectForKey:key];
		}
	}];

	[object setValuesForKeysWithDictionary:workingJSONRepresentation];

	return object;
}

+ (NSString *__nullable) replacementKeyForKey:(NSString *) key {
	if ([key isEqual:@"id"]) {
		return @"identifier";
	}

	if ([key isEqual:@"description"]) {
		return @"objectDescription";
	}

	return nil;
}

+ (NSFormatter *__nullable) formatterForKey:(NSString *) key {
	return nil;
}

+ (NSValueTransformer *__nullable) transformerForKey:(NSString *) key {
	return nil;
}

#pragma mark -

+ (BOOL)supportsSecureCoding {
	return YES;
}

- (__nullable id) initWithCoder:(NSCoder *) aDecoder {
	if (!(self = [super init])) {
		return nil;
	}

	[self _enumeratePropertiesWithPropertyStartBlock:nil propertyBlock:^(NSString *key, id __nullable value) {
		objc_property_t property = class_getProperty([self class], key.UTF8String);
		NSString *attributes = [NSString stringWithUTF8String:property_getAttributes(property)];
		NSArray *attributesComponents = [attributes componentsSeparatedByString:@","];
		NSString *encodedClassString = attributesComponents.firstObject;

		if (encodedClassString) {
			NSArray *encodedClassComponents = [encodedClassString componentsSeparatedByString:@"\""];
			NSString *classString = encodedClassComponents.firstObject;
			if (classString) {
				Class klass = NSClassFromString(classString);
				[self setValue:[aDecoder decodeObjectOfClass:klass forKey:key] forKey:key];
			}
		}
	} completionBlock:nil];

	return self;
}

- (void) encodeWithCoder:(NSCoder *) aCoder {
	[self _enumeratePropertiesWithPropertyStartBlock:nil propertyBlock:^(NSString *key, id __nullable value) {
		[aCoder encodeObject:value forKey:key];
	} completionBlock:nil];
}

#pragma mark -

- (id) copyWithZone:(nullable NSZone *) zone {
	id copy = [[[self class] alloc] init];
	[self _enumeratePropertiesWithPropertyStartBlock:nil propertyBlock:^(NSString *key, id __nullable value) {
		[copy setValue:value forKey:key];
	} completionBlock:nil];
	return copy;
}

#pragma mark -

- (void) setValue:(nullable id) value forKey:(NSString *) key {
	NSError *error = nil;
	if ([self validateValue:&value forKey:key error:&error]) {
		[super setValue:value forKey:key];
	}
}

- (void) setNilValueForKey:(NSString *) key {
	NSLog(@"Refusing to set nil value for key");
}

- (void) setValue:(nullable id) value forUndefinedKey:(NSString *) key {
	NSLog(@"%@: Refusing to set value \"%@\" for unknown key \"%@\"", NSStringFromClass([self class]), value, key);
}

- (BOOL) validateValue:(inout id *) ioValue forKey:(NSString *) inKey error:(out NSError **) outError {
	NSString *value = *ioValue;
	if (![value isKindOfClass:[NSString class]]) {
		return YES;
	}

	BOOL validValue = YES;
	NSValueTransformer *transformer = [[self class] transformerForKey:inKey];
	if (transformer) {
		*ioValue = [transformer transformedValue:*ioValue];
	}

	NSFormatter *formatter = [[self class] formatterForKey:inKey];
	if (formatter) {
		validValue = [formatter getObjectValue:ioValue forString:value errorDescription:nil];
	}

	return validValue;
}

#pragma mark -

- (NSString *) description {
	NSMutableString *propertyDescription = [[super description] mutableCopy];

	[self _enumeratePropertiesWithPropertyStartBlock:^(NSUInteger propertyCount) {
		if (propertyCount) {
			[propertyDescription appendString:@"\t{"];
		}
	} propertyBlock:^(NSString *__nonnull key, id value) {
		[propertyDescription appendFormat: @"\n\t%@: %@,", key, value];
	} completionBlock:^(NSUInteger propertyCount) {
		if (propertyCount) {
			[propertyDescription deleteCharactersInRange:NSMakeRange(propertyDescription.length - 1, 1)];
			[propertyDescription appendString:@"\n}"];
		}
	}];

	return [propertyDescription copy];
}

#pragma mark -

- (void) _enumeratePropertiesWithPropertyStartBlock:(void(^__nullable)(NSUInteger)) startBlock propertyBlock:(void(^)(NSString *, id __nullable)) propertyBlock completionBlock:(void(^__nullable)(NSUInteger)) completionBlock {
	unsigned int propertyCount = 0;
	objc_property_t *propertyList = class_copyPropertyList([self class], &propertyCount);
	if (startBlock) {
		startBlock(propertyCount);
	}

	if (propertyCount) {
		for (unsigned int i = 0; i < propertyCount; i++) {
			objc_property_t property = propertyList[i];
			const char *propertyNameCString = property_getName(property);
			NSString *propertyNameString = [NSString stringWithUTF8String:propertyNameCString];
			id value = [self valueForKey:propertyNameString];

			propertyBlock(propertyNameString, value);
		}

		free(propertyList);
	}

	if (completionBlock) {
		completionBlock(propertyCount);
	}
}
@end

NS_ASSUME_NONNULL_END

B.h

#import "WObject.h"

@interface WFlight : WObject
@property (copy) NSDate *actTime;
@property (copy) NSString *arrCityName1;
@property (copy) NSString *arrCityName2;
@property (copy) NSString *arrCityName3;
@property (copy) NSString *bagClaim;
@property (copy) NSString *baseFlight;
@property (copy) NSString *baseFlightCarrier;
@property (copy) NSString *carrier;
@property (copy) NSString *carrierFull;
@property (copy) NSString *city1;
@property (copy) NSString *city2;
@property (copy) NSString *city3;
@property (copy) NSString *cityCode;
@property (copy) NSString *cityFull;
@property (copy) NSString *depCityName1;
@property (copy) NSString *depCityName2;
@property (copy) NSString *depCityName3;
@property (copy) NSDate *estTime;
@property (copy) NSDate *estTimeMili;
@property (copy) NSNumber *flightNum;
@property (copy) NSString *flightNumFull;
@property (copy) NSString *flightType;
@property (copy) NSString *gate;
@property (copy) NSString *origin;
@property (copy) NSString *remark;
@property (copy) NSDate *schedTime;
@property (copy) NSDate *schedTimeMili;
@property (copy) NSString *terminal;
@property (copy) NSDate *addedTimestamp;
@property (copy) NSString *iGate;
@property (copy) NSString *inc;
@property (copy) NSDate *lastUpdated;
@end

B.m

#import "WFlight.h"

NS_ASSUME_NONNULL_BEGIN

@interface WEpochDateTransformer : NSValueTransformer
@end

@implementation WEpochDateTransformer
+ (BOOL) allowsReverseTransformation {
	return YES;
}

+ (Class)transformedValueClass {
	return [NSDate class];
}

- (nullable id) transformedValue:(nullable id) value {
	return [NSDate dateWithTimeIntervalSince1970:[value doubleValue]];
}

- (nullable id) reverseTransformedValue:(nullable id) value {
	return @([value timeIntervalSince1970]);
}
@end

@implementation WFlight
+ (void)initialize {
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		[NSValueTransformer setValueTransformer:[[self alloc] init] forName:NSStringFromClass([self class])];
	});
}

+ (NSString *__nullable) replacementKeyForKey:(NSString *__nonnull) key {
	NSString *replacementKey = nil;
	if ([[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[key characterAtIndex:0]]) {
		NSString *lowercaseString = [key substringToIndex:1].lowercaseString;
		replacementKey = [key stringByReplacingCharactersInRange:NSMakeRange(0, 1) withString:lowercaseString];
	}

	if ([key isEqual:@"added_ts"]) {
		replacementKey = NSStringFromSelector(@selector(addedTimestamp));
	} else if ([key isEqual:@"lastupdated"]) {
		replacementKey = NSStringFromSelector(@selector(lastUpdated));
	}

	return replacementKey ?: [super replacementKeyForKey:key];
}

+ (NSFormatter *__nullable) formatterForKey:(NSString *__nonnull) key {
	NSDateFormatter *(^dateFormatterWithFormat)(NSString *) = ^NSDateFormatter *(NSString *format) {
		static NSMutableDictionary *dateFormatters = nil;
		static dispatch_once_t onceToken;
		dispatch_once(&onceToken, ^{
			dateFormatters = [NSMutableDictionary dictionary];
		});

		NSDateFormatter *dateFormatter = dateFormatters[format];
		if (!dateFormatter) {
			dateFormatter = [[NSDateFormatter alloc] init];
			dateFormatter.dateFormat = format;
			dateFormatter.timeZone = [NSTimeZone timeZoneWithName:@"PST"]; // todo: this means PST // todo: don't assume SFO/OAK

			dateFormatters[format] = dateFormatter;
		}

		return dateFormatter;
	};

	static NSArray *hhmmaProperties = nil;
	if (!hhmmaProperties) {
		hhmmaProperties = @[ NSStringFromSelector(@selector(estTime)), NSStringFromSelector(@selector(schedTime)) ];
	}
	if ([hhmmaProperties containsObject:key]) {
		return dateFormatterWithFormat(@"hh:mm a");
	}

	static NSArray *HHmmProperties = nil;
	if (!HHmmProperties) {
		HHmmProperties = @[ NSStringFromSelector(@selector(estTimeMili)), NSStringFromSelector(@selector(schedTimeMili)) ];
	}
	if ([HHmmProperties containsObject:key]) {
		return dateFormatterWithFormat(@"HH:mm");
	}

	static NSArray *MMddyyyyhhmma = nil;
	if (!MMddyyyyhhmma) {
		MMddyyyyhhmma = @[ NSStringFromSelector(@selector(lastUpdated)) ];
	}
	if ([MMddyyyyhhmma containsObject:key]) {
		return dateFormatterWithFormat(@"MM/dd/yyyy HH:mm a");
	}

	return [super formatterForKey:key];
}

+ (NSValueTransformer *__nullable)transformerForKey:(NSString *) key {
	NSArray *epochTimestamp = @[ NSStringFromSelector(@selector(addedTimestamp)) ];
	if ([epochTimestamp containsObject:key]) {
		return [NSValueTransformer valueTransformerForName:NSStringFromClass([WEpochDateTransformer class])];
	}

	return [super transformerForKey:key];
}

- (BOOL) isEqual:(id) object {
	if (!object || ![object isKindOfClass:[self class]]) {
		return NO;
	}

	return [self.flightNumFull isEqual:[object flightNumFull]];
}

- (NSUInteger) hash {
	return self.flightNumFull.hash;
}
@end

NS_ASSUME_NONNULL_END