UISplitViewController：如何呈現popover？

Question

我有一個UISplitViewController這是一個UISplitViewControllerDelegate具有以下的委託方法：

splitViewController:willHideViewController:withBarButtonItem:forPopoverController:

當iPad在肖像開始，我想酥料餅從SPLITVIEW可見。我怎樣才能做到這一點？

我試過下面的代碼：

- (void)splitViewController:(UISplitViewController *)svc 
    willHideViewController:(UIViewController *)aViewController 
      withBarButtonItem:(UIBarButtonItem *)barButtonItem 
     forPopoverController:(UIPopoverController *)pc 
{ 
    //setting the barButtonItem in the toolbar in the detail view. 

    [pc presentPopoverFromBarButtonItem:barButtonItem permittedArrowDirections:UIPopoverArrowDirectionAny animated:NO]; 
} 

但上面的代碼給我下面的錯誤：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIPopoverController presentPopoverFromRect:inView:permittedArrowDirections:animated:]: Popovers cannot be presented from a view which does not have a window.'

Answer 1

那裏只有一個問題，錯誤的地點調用presentPopover方法，splitViewController： * WillHide * ViewController .......所以，barButtonItem存在但不在屏幕上。我使用下一個代碼，它爲我工作。 爲了處理所有情況，你需要使用2種方法。

- (void)viewDidAppear:(BOOL)animated 
{ 
    if ([[UIDevice currentDevice] orientation] == UIDeviceOrientationPortrait || [[UIDevice currentDevice] orientation] == UIDeviceOrientationPortraitUpsideDown) { 
     if (self.view.window != nil) { 
      [_masterPopoverController presentPopoverFromRect:CGRectMake(0, 0, 1, 1) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:NO]; 
     } 
    } 
    [super viewDidAppear:animated]; 
} 

和

-(void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation 
{ 
    if (fromInterfaceOrientation == UIDeviceOrientationLandscapeLeft || fromInterfaceOrientation == UIDeviceOrientationLandscapeRight) { 
     if (self.view.window != nil) { 
      [_masterPopoverController presentPopoverFromRect:CGRectMake(0, 0, 1, 1) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionUp animated:NO]; 
     } 
    } 
}