<p>Can one be simulated by periodicly syncing with GPS and in the meen while working with the accelerometer? I know for example that the N95 accelerometer is invarient to rotation on the Y axis (while beeing face up/down).</p>

[{'answer_id': 42756, 'author': 'different', 'author_id': 3654, 'author_profile': 'https://Stackoverflow.com/users/3654', 'pm_score': 2, 'selected': False, 'text': '<p>iPhone doesn\'t have a built in compass; but there is one created in software. It\'s called <em><a href="http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=284735786&amp;mt=8" rel="nofollow noreferrer">Compass Free</a></em>, and unsurprisingly perhaps, it\'s free.</p>\n'}, {'answer_id': 43156, 'author': 'jm.', 'author_id': 814, 'author_profile': 'https://Stackoverflow.com/users/814', 'pm_score': 0, 'selected': False, 'text': '<p>Extra info: The IPHONE 1 did not have GPS or compass.</p>\n'}, {'answer_id': 1534595, 'author': 'Nick Bedford', 'author_id': 151429, 'author_profile': 'https://Stackoverflow.com/users/151429', 'pm_score': 3, 'selected': True, 'text': '<p>The original iPhone and the iPhone 3G use GPS to calculate the heading, however the iPhone 3GS now has a 3-dimensional magnetometer compass in it.</p>\n\n<p>This can only be done taking two GPS coordinates (while moving) and determining the direction from point A to B.</p>\n'}]
['https://Stackoverflow.com/questions/42749', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/44972/']