即使未在 - (NSUInteger)supportedInterfaceOrientations中定义,也检测UIViewController上的接口旋转

Question

我有一个UIViewController在主视图上处理几个UIImageViews.在底部是一个UIToolbar,其中有几个项目可以与之交互.

现在,当我旋转设备时,我不希望viewController旋转,而只是UIImageViews.换句话说,底部的工具栏将位于左侧(或右侧),但imageViews将正确旋转.

所以,通过使用方法

- (BOOL)shouldAutoRotate {
   return YES;
}

结合

- (NSUInteger)supportedInterfaceOrientations {
   return UIInterfaceOrientationMaskPortrait;
}

和

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
// rotate the image views here
}

设备上的任何旋转都不会被执行,因为只支持一个接口方向(UIInterfaceOrientationMaskPortrait).但是当我在supportedInterfaceOrientations-method中添加另一个支持的接口方向时,视图控制器也会旋转.

即使只支持一个方向,如何检测视图控制器的旋转？或者是否有另一种可能性根据不断变化的设备方向旋转UIViews？

谢谢你的帮助!

Answer 1

尝试使用UIDevice实例来检测设备物理方向的变化.要开始接收通知,您可以使用类似的东西(viewWillAppear:例如在方法中):

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];

    //No reason to ask NSNotification because it many cases `userInfo` equals to
    //@{UIDeviceOrientationRotateAnimatedUserInfoKey = 1;}
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceDidRotate) name:@UIDeviceOrientationDidChangeNotification object:nil];
}

要取消注册接收设备旋转事件,请使用此(viewWillDisappear:例如):

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];

    [[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}

这是一个deviceDidRotate功能的例子:

- (void)deviceDidRotate {
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

    switch (orientation) {
        case UIDeviceOrientationPortrait:
        case UIDeviceOrientationPortraitUpsideDown:
            // do something for portrait orientation
            break;
        case UIDeviceOrientationLandscapeLeft:
        case UIDeviceOrientationLandscapeRight:
            // do something for landscape orientation
            break;

        default:
            break;
    }
}