IPhone OS4 feature link error while run on OS3.x
<p>I've compiled an app with IPhone base SDK 4.0, deployment target on iPhone OS 3.0. This app contains OS 4.0 new feature: local notification. </p>

<p>It works well on iPod 2G with OS 4.0; however it crashes every time the app start up on iPhone 1G with OS 3.0. It appears to be runtime reference error:</p>

<p>"dyld: Symbol not found: _OBJC_CLASS_$_UILocalNotification
  Referenced from: /var/mobile/Applications/73A3FAB1-63AE-4A71-8C6B-932142A728FE/Tapatalk X.app/Tapatalk X
  Expected in: /System/Library/Frameworks/UIKit.framework/UIKit"</p>

<p>If the UIKit framework is different between SDK3.0 &amp; SDK4.0, why it doesn't report while compiling? How can I apply local notification feature on this app, while the app can still running on devices with OS3.0? Thanks. </p>
