UIButton events
<p>using iphone SDK 4.0. I have some UIButtons in a viewcontroller which when touched should play a tone, and when released stop playing the tone. This is done so that the tone length depends on how long the button is held down. </p>

<p>I use the Touch down event for when i call [toneplay start] and the TouchUpInside event
for when i call [toneplay stop]. </p>

<p>A problem i have discovered is that if after touching a button i quickly navigate to another viewcontroller ( via tab bar button for example) the TouchUpInside event never fires and so the tone never stops playing unless i navigate back to the screen and hit the same button.</p>

<p>What would be the correct way to do this, the actual method to play the tone doesn't matter here its more which UIButton events i should really be using to get the above functionality.</p>

<p>Thanks</p>
