当iPhone进入景观模式时执行方法。

Is there a delegate that will get called when the iPhone enters landscape or portrait mode? I need to change the style and place objects in a different place when the iPhone get's rotated. Do I have to do this with the accelerometer? Moreover if there exist such a delegate do I have to create the connection in interface builder. I am new to objective-c... Is there a delegate that will get called when t