<< operator in objective c enum?

Question

I was looking for something and got in to this enum is apple UITableViewCell.h.

I am sorry if this is trivial but I wonder/curious what is the point of this.

I

Answer 1

These operand called bitshift. Bitshift operand can be preferred for 2 reasons. - For fast operation - Use multiple bool value in one time.

For example : 1<<2 is a left shift; that means 1 : 0001, 2 : 0010

1 << 2 this line means is 2 should be left one bit. As a result 0010 shifted to 0100

Also shifted value must ordered as a 1,2,4,8,16...

typedef NS_OPTIONS(int, EntityEngineer) {
EntityEngineeriOS = 1 << 0,
EntityCategoryAndroid = 1 << 1,
EntityCategoryDB = 1 << 2,
EntityCategoryTeamLead = 1 << 16,};

Now, we want to check mutiple boolean in below line,

char engineer = (EntityEngineeriOS | EntityCategoryAndroid);

char 0011 = (0001 | 0010);

if (engineer & EntityEngineeriOS) {
    NSLog(@"we are looking for a developer who can write objective c or java");
}

if (engineer & EntityCategoryDB) {
    NSLog(@"we are not looking for a DB manager");
}

Result : we are looking for a developer who can write objective c or java