Please explain the use of bitwise operator OR in NSDateComponents?

Question

I can't seem to find an answer to this. Here nor documentation. Maybe I'm not sure what I should be looking for?

unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;

From my understanding those should be logical bitwise operators for "OR"

How do they work in this situation?

Answer 1

bitwise operators used like this is a way of setting multiple boolean flags in one variable, called a bitmask

so if

FlagA = 1 << 3; //binary = 1000
FlagB = 1 << 2; //binary = 0100
FlagC = 1 << 1; //binary = 0010
FlagD = 1 << 0; //binary = 0001

and i set

myFlag = FlagA | FlagC | FlagD;

it is the or of

1000 |
0010 |
0001 =
1011

So in your example you are setting the unit flags to be Hour, Minute, Day and Month