There was a great question on Stack Overflow today about how to catch media key events (such as play/pause or seek forward/backward) in your own app. I thought I’d post the solution I use in Transcriva.
My approach (which may not be the only or best approach) was to subclass NSApplication and catch calls to -sendEvent: (through which keyboard events, among other kinds, are sent). If the event is a media key press, I translate it to the appropriate action call to my app delegate.
The complete (relevant) code listing:
import
(void)sendEvent:(NSEvent *)event
{
// Catch media key events
if ([event type] == NSSystemDefined && [event subtype] == 8)
{
int keyCode = (([event data1] & 0xFFFF0000) >> 16);
int keyFlags = ([event data1] & 0x0000FFFF);
int keyState = (((keyFlags & 0xFF00) >> 8)) == 0xA;
// Process the media key event and return
[self mediaKeyEvent:keyCode state:keyState];
return;
}
// Continue on to super
[super sendEvent:event];
}
(void)mediaKeyEvent:(int)key state:(BOOL)state
{
switch (key)
{
// Play pressed
case NX_KEYTYPE_PLAY:
if (state == NO)
[(TSAppController *)[self delegate] togglePlayPause:self];
break;
// Rewind
case NX_KEYTYPE_FAST:
if (state == YES)
[(TSAppController *)[self delegate] seekForward:self];
break;
// Previous
case NX_KEYTYPE_REWIND:
if (state == YES)
[(TSAppController *)[self delegate] seekBack:self];
break;
}
}
Just remember to set your app’s principal class to your new NSApplication subclass (see below) and implement the -togglePlayPause:, -seekForward:, and -seekBack: actions in your app delegate (and make sure you have an app delegate).
