设置UIImagePickerController委托会抛出有关UINavigationControllerDelegate的警告

The code:

代码：

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
[self.navigationController presentModalViewController:picker animated:YES];
[picker release];
UIImagePickerController *pick