当我的孩子执行展开时,我的控制器的viewDidAppear被调用.
注意：孩子正在放松到第一个视图控制器,所以这是一个中间视图控制器,而不是真正的根.
解决方法
如果视图控制器的曝光是由于被推送/呈现而导致的,或者由于弹出/关闭/展开而导致暴露,则应该能够使用以下内容来检测每个控制器.
这可能或可能足以满足您的需求.
- (void) viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
// Handle controller being exposed from push/present or pop/dismiss
if (self.isMovingToParentViewController || self.isBeingPresented){
// Controller is being pushed on or presented.
}
else{
// Controller is being shown as result of pop/dismiss/unwind.
}
}
如果你想知道viewDidAppear是被调用的,因为一个放松的segue与传统的pop / dismiss被调用不同,那么你需要添加一些代码来检测是否发生了一个展开.为此,您可以执行以下操作：
对于任何中间控制器,您只需要检测出来,就可以添加以下形式的属性：
/** BOOL property which when TRUE indicates an unwind occured. */ @property BOOL unwindSeguePerformed;
然后覆盖展开方法canPerformUnwindSegueAction：fromViewController：withSender：方法如下：
- (BOOL)canPerformUnwindSegueAction:(SEL)action
fromViewController:(UIViewController *)fromViewController
withSender:(id)sender{
// Set the flag indicating an unwind segue was requested and then return
// that we are not interested in performing the unwind action.
self.unwindSeguePerformed = TRUE;
// We are not interested in performing it,so return NO. The system will
// then continue to look backwards through the view controllers for the
// controller that will handle it.
return NO;
}
现在你有一个标志来检测放松和一种在发生之前检测放松的方法.然后调整viewDidAppear方法来包含这个标志.
- (void) viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
// Handle controller being exposed from push/present or pop/dismiss
// or an unwind
if (self.isMovingToParentViewController || self.isBeingPresented){
// Controller is being pushed on or presented.
// Initialize the unwind segue tracking flag.
self.unwindSeguePerformed = FALSE;
}
else if (self.unwindSeguePerformed){
// Controller is being shown as a result of an unwind segue
}
else{
// Controller is being shown as result of pop/dismiss.
}
}
希望这符合您的要求.
有关处理展开链的文档,请参阅：https://developer.apple.com/library/ios/technotes/tn2298/_index.html
