iOS判断对象相等 重写isEqual、isEqualToClass、hash

@interface Person
@property NSString *name;
@property NSDate *birthday;

- (BOOL)isEqualToPerson:(Person *)person;
@end

@implementation Person

- (BOOL)isEqualToPerson:(Person *)person {
if (!person) {
return NO;
}

BOOL haveEqualNames = (!self.name && !person.name) || [self.name isEqualToString:person.name];
BOOL haveEqualBirthdays = (!self.birthday && !person.birthday) || [self.birthday isEqualToDate:person.birthday];

return haveEqualNames && haveEqualBirthdays;
}

#pragma mark - NSObject

- (BOOL)isEqual:(id)object {
if (self == object) {
return YES;
}

if (![object isKindOfClass:[Person class]]) {
return NO;
}

return [self isEqualToPerson:(Person *)object];
}

- (NSUInteger)hash {
return [self.name hash] ^ [self.birthday hash];
}