Quick (untested) example of getting bar-beat time for a particular timestamp in an MIKMIDISequence.

MIKMIDISequence+BarBeatTime.m

@interface MIKMIDISequence (BarBeatTime)
- (CABarBeatTime)barBeatTimeForTimeStamp:(MusicTimeStamp)timeStamp error:(NSError **)error;
@end

@implementation MIKMIDISequence (BarBeatTime)

- (CABarBeatTime)barBeatTimeForTimeStamp:(MusicTimeStamp)timeStamp error:(NSError **)error
{
	error = error ?: &(NSError *__autoreleasing){ nil };
	UInt32 timeResolution = 0;
	UInt32 propertyLength = 0;
	OSStatus err = MusicTrackGetProperty(self.tempoTrack.musicTrack,
										 kSequenceTrackProperty_TimeResolution,
										 NULL,
										 &propertyLength);
	if (err != noErr) {
		*error = [NSError errorWithDomain:NSOSStatusErrorDomain code:err userInfo:nil];
		return (CABarBeatTime){0};
	}
	err = MusicTrackGetProperty(self.tempoTrack.musicTrack,
						  kSequenceTrackProperty_TimeResolution,
						  &timeResolution,
						  &propertyLength);
	if (err != noErr) {
		*error = [NSError errorWithDomain:NSOSStatusErrorDomain code:err userInfo:nil];
		return (CABarBeatTime){0};
	}
	
	CABarBeatTime barBeatTime = {0};
	err = MusicSequenceBeatsToBarBeatTime(self.musicSequence, timeStamp, timeResolution, &barBeatTime);
	if (err != noErr) {
		*error = [NSError errorWithDomain:NSOSStatusErrorDomain code:err userInfo:nil];
		return (CABarBeatTime){0};
	}
	return barBeatTime;
}

@end