确定UIMenuController何时被解除?

状态更改时,UIMenuController将通知发布到默认的NSNotification center。您可以订阅它们,以便在系统隐藏菜单时获得通知:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willHideEditMenu:) name:UIMenuControllerWillHideMenuNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didHideEditMenu:) name:UIMenuControllerDidHideMenuNotification object:nil];

基于@Markus Mller的建议,您可以复制以下模式:

- (BOOL)becomeFirstResponder
{
    // starts listening for UIMenuControllerDidHideMenuNotification & triggers resignFirstResponder if received
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(resignFirstResponder) name:UIMenuControllerDidHideMenuNotification object:nil];
    return [super becomeFirstResponder];
}

- (BOOL)resignFirstResponder
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIMenuControllerDidHideMenuNotification object:nil];

    // your custom cleanup code here (e.g. deselection)

    return [super resignFirstResponder];
}

在我的例子中,我有数百个可选择的对象,所以我不想要它们 全部的 全部的 resignFirstResponder 当菜单被取消,并以相同的方式结束观察时。

在我的情况下(如在OP的),因为该项目是不可编辑的,它是可取的,我呼吁 辞职第一响应者 当菜单取消时。这种方式, 辞职第一响应者

NotificationCenter.default.addObserver(
   self,
   selector: #selector(self.didHideEditMenu),
   name: NSNotification.Name.UIMenuControllerDidHideMenu,
   object: nil)

NotificationCenter.default.addObserver(
   self,
   selector: #selector(self.willHideEditMenu),
   name: NSNotification.Name.UIMenuControllerWillHideMenu,
   object: nil)

Swift 5号

NotificationCenter.default.addObserver(
        self,
        selector: #selector(willHideMenu),
        name: UIMenuController.willHideMenuNotification,
        object: nil)