objective-c - 如何检测以编程方式生成的 UIView 的旋转

Question

我有一个以编程方式创建的 UIView:

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
    if (self) {
        self.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:.5];

        UIImageView* closeButton = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"modal_close.png"]];

        closeButton.frame = CGRectMake(self.frame.size.width*.89, self.frame.size.height*.09, closeButton.frame.size.width, closeButton.frame.size.height);

        UIButton* button = [[UIButton alloc] initWithFrame:CGRectMake(self.frame.size.width*.89, self.frame.size.height*.09,20, 20)];

        [button addTarget:self action:@selector(close) forControlEvents:UIControlEventTouchUpInside];

        UIView* mainView = [[UIView alloc] initWithFrame:CGRectMake(self.frame.size.width*.1,self.frame.size.height*.1,self.frame.size.width*.8,self.frame.size.height*.8)];

        mainView.backgroundColor = [UIColor whiteColor];
        _displayMainView = mainView;        

        [self addSubview:_displayMainView];
        [self addSubview:closeButton];
        [self addSubview:button];

        mainView = nil;
        closeButton = nil;
    }
    return self;
}

如何检测旋转？这是作为另一个现有 View 之上的模态。如果重要的话，这是一款仅限 iPad 的应用程序。

Answer 1

您可以让设备开始生成旋转通知:

  [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];

添加您自己的选择器作为设备旋转通知的观察者:

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

然后编写你的通知处理程序

- (void)deviceOrientationDidChange:(NSNotification *)notification {
     //Obtain current device orientation
     UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

      //Do my thing
 }

请记住在调用自定义 UIView 的 dealloc 方法时(或完成时)移除观察者，并停止生成设备更改通知。

-(void) dealloc{
[[NSNotificationCenter defaultCenter] removeObserver: self];
[[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
}

这对您的问题有帮助吗？