How to encode and decode NSCalendarUnit

Question

How to encode and decode NSCalendarUnit like other objects, like

self.myStr = [decoder decodeObjectForKey:@"myStr"];
[encoder encodeObject:self.myStr forKey:@"myStr"];

Tried to save NSCalendarUnit in NSNumber like this @(self.repetition); but I am getting 64 when I log.

I want to encode NSCalendarUnit and save it, later when required decode it and use it for comparison like this if(xxxxx == NSCalendarUnit)

Answer 1

NSCalendarUnit is an option set ( NS_OPTIONS ), which means a NSCalendarUnit value can be none, one, or more values of the units. You'll need to do a bit mask if ((xxxx & NSCalendarUnitHour) != 0) to check for values.

You're fine encoding the value like you are now, as a NSNumber and using NSNumber.unsignedInteger to get the value when decoding (note that the enum for NSCalendarUnit is defined as a NSUInteger ). (Note you can also store the value as a NSInteger using -[NSCoder encodeInteger:forKey:] .)

Serialisation

[encoder encodeObject:@(self.repetition) forKey:@"repetition"];

Deserialisation

self.repetition = [[decoder decodeObjectOfClass:[NSNumber class] 
                   forKey:@"repetition"] unsignedInteger];

Checking

if ((self.repetition & NSCalendarUnitHour) != 0) {
    // Do something
} else if ((self.repetition & NSCalendarUnitMinute) != 0) {
    // Do something
}

Answer 2

NSCalendarUnit is an unsigned long, so it can be "boxed" (made into an object) using two methods on NSNumber intended for unsigned longs:

NSCalendarUnit someNSCalendarUnit = NSCalendarUnitDay;
NSNumber *boxed = [NSNumber numberWithUnsignedLong:someNSCalendarUnit];

and

NSCalendarUnit unboxed = [boxed unsignedLongLongValue];
// now, unboxed == someNSCalendarUnit

And you probably know how to encode an decode NSNumbers, just add the additional box-step to the encode/decode methods...

- (void)encodeWithCoder:(NSCoder*)encoder {
    [super encodeWithCoder:encoder];

    NSNumber *boxed = [NSNumber numberWithUnsignedLong:self.someNSCalendarUnit];
    [encoder encodeObject:boxed forKey:@"someNSCalendarUnit"];
    // ...

}

- (id)initWithCoder:(NSCoder*)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        NSNumber *boxed = [aDecoder decodeObjectForKey:@"someNSCalendarUnit"];
        _someNSCalendarUnit = [boxed unsignedLongLongValue];
        // ...
    }
    return self;
}