camera 自定义 overlay 横屏的方法

有没有谁能给我一个列子，是用UIImagePickerController调用camera，然后通过cameraOverlayView自定义一个横屏的拍照模式的例子。而且在横屏上，要能自己添加一些按钮控件等。我找了半天没有找到。谢谢！

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UIImagePickerController *iPicker = [[UIImagePickerController alloc] init];
iPicker.showsCameraControls = NO;
UIView *parentView=[[[UIView alloc] initWithFrame:CGRectMake(0,0,[[UIScreen mainScreen] bounds].size.width, [[UIScreen mainScreen] bounds].size.height)] autorelease];
//在parentView里面自定义按钮
iPicker.cameraOverlayView = parentView;