NSEvent commandKey not detected

Question

I'm trying to detect whether the command key is pressed, and for the life of me cannot figure out what is wrong with the following. I've overridden a view to provide the code below:

- (void)flagsChanged:(NSEvent *)theEvent {

    NSLog(@"flags changed in %@", self);
    BOOL commandKeyPressed = ([theEvent modifierFlags] & NSCommandKeyMask);

    if (commandKeyPressed)
        NSLog(@"command key in %@", self);
}

I see the "flags changed" message whenever I press the command key, but not the "command key in" message. What am I missing?

Answer 1

A BOOL is a signed char, so when you convert an int to a BOOL, you lop off all but the low 8 bits. And in your case, the nonzero bit is not in the low 8 bits. Instead, say

BOOL commandKeyPressed = ([theEvent modifierFlags] & NSCommandKeyMask) != 0;

or just

if ([theEvent modifierFlags] & NSCommandKeyMask)