Motion detection using iPhone
<p>I saw at least 6 apps in AppStore that take photos when detect motion (i.e. a kind of Spy stuff). Does anybody know what is a general way to do such thing using iPhone SDK? </p>

<p>I guess their apps take photos each X seconds and compare current image with previous to determine if there any difference (read "motion"). Any better ideas? </p>

<p>Thank you!</p>
