iphone - 如何在不允许旋转其界面的 Controller 中旋转 View ？

Question

帮我解决这个任务 - 我有一个不允许旋转其界面的 viewController:

- (BOOL)shouldAutorotate {
    return NO;
}

- (NSUInteger)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskPortrait;
}

但我需要旋转出现在该 Controller 中的 alertView!因此，如果用户旋转设备，alertView 应该跟随旋转并且主界面保持静止。我尝试订阅通知:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceRotated:) name:UIDeviceOrientationDidChangeNotification object:nil];

但在我的 deviceRotated:我收到带有此类有效负载的通知: NSConcreteNotification 0x101dc50 {name = UIDeviceOrientationDidChangeNotification; object = <UIDevice: 0x103e640>; userInfo = {
UIDeviceOrientationRotateAnimatedUserInfoKey = 1;
}}

什么是 UIDeviceOrientationRotateAnimatedUserInfoKey ？我如何使用知道当前的 interfaceOrientation？或者建议一种更好的获取当前方向和旋转 alertView 的方法。

我试过

(BOOL)shouldAutorotateToInterfaceOrientation:UIInterfaceOrientation)toInterfaceOrientation

和

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration但是这些方法不会在 iOS6 上被调用:(

此外，是否有任何其他方法可用于了解设备正在旋转到某个方向？提前致谢!附言我知道这个任务看起来有点傻，但这是客户的说法。对不起:)

Answer 1

UIDevice 中有一个orientation 变量，它包含当前设备方向。您可以使用它代替界面方向(不会像您已经注意到的那样旋转)。

首先，您订阅设备方向更改，一个好的地方是 viewWillAppear 并取消订阅 viewWillDisappear:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(orientationChanged:)
                                                 name:UIDeviceOrientationDidChangeNotification
                                               object:nil];
    [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

在这个例子中，我们表示我们希望在设备旋转时调用 orientationChanged:，所以让我们实现它:

#pragma mark - Orientation change events
- (void)orientationChanged:(NSNotification*)notification {
    UIDeviceOrientation deviceOrientation = [[UIDevice currentDevice] orientation];

    // Calculate rotation angle
    CGFloat angle;
    switch (deviceOrientation) {
        case UIDeviceOrientationPortraitUpsideDown:
            angle = M_PI;
            break;
        case UIDeviceOrientationLandscapeLeft:
            angle = M_PI_2;
            break;
        case UIDeviceOrientationLandscapeRight:
            angle = - M_PI_2;
            break;
        default:
            angle = 0;
            break;
    }

    // Apply rotation
    static NSTimeInterval animationDuration = 0.3;
    [UIView animateWithDuration:animationDuration animations:^{
        _viewToRotate.transform = CGAffineTransformMakeRotation(angle);
    }];
}