我可以观察UIViewController何时更改i​​nterfaceOrientation？

Question

如果我有一个指向UIViewController的指针，是否可以在更改interfaceOrientation时通知我而不修改控制器的代码？

我最好选择检测设备方向的变化，然后看看UIViewController是否会旋转（d）？

Answer 1

您可以使用NSNotificationCenter：

 [[NSNotificationCenter defaultCenter] addObserver:self // put here the view controller which has to be notified
                                         selector:@selector(orientationChanged:)
                                             name:@"UIDeviceOrientationDidChangeNotification" 
                                           object:nil];
- (void)orientationChanged:(NSNotification *)notification{  
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

    //do stuff
    NSLog(@"Orientation changed");          
}

Answer 2

您可以在UIViewController上使用willAnimateRotationToInterfaceOrientation:duration:方法，然后为横向或纵向重新定位任何UIViews（或任何其他代码）。 E.g。

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
  if (toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft || toInterfaceOrientation == UIInterfaceOrientationLandscapeRight) {
    // change positions etc of any UIViews for Landscape
  } else {
    // change position etc for Portait
  }

  // forward the rotation to any child view controllers if required
  [self.rootViewController willAnimateRotationToInterfaceOrientation:toInterfaceOrientation duration:duration];
}