Example of setting, getting, toggling and clearing bits. Source: http://iosdevelopertips.com/c/creating-bit-fields-in-c-and-objective-c.html

BitsExample

#define BIT_ONE   1
#define BIT_TWO   2
#define BIT_THREE 4
#define BIT_FOUR  8
 
int flag = 0;
 
// Set bits
flag |= BIT_ONE | BIT_THREE;
NSLog(@"Bits: %@", [self intToBinaryString:flag]);
 
// Clear bits
flag &= ~(BIT_ONE | BIT_THREE);
NSLog(@"Bits: %@", [self intToBinaryString:flag]);
 
// Toggle bit
flag ^= (BIT_ONE | BIT_THREE);
NSLog(@"Bits: %@", [self intToBinaryString:flag]);
 
// Check bits
if (flag & (BIT_ONE | BIT_THREE))
  NSLog(@"Bits set");
else
  NSLog(@"Bits not set");