How can I find the UIPopoverController from the UIViewController being displayed in a popover?

My recommendation is to leverage a combination of your own custom property and the private APIs in UIKit. To avoid app store rejection, any private APIs should compile out for release builds, and should be used only to check against your implementation.

First let's build the custom property into a category on UIViewController. This allows some perks in the implementation, and it doesn't require you to go back and derive every class from some custom view controller subclass.

// UIViewController+isPresentedInPopover.h

#import <UIKit/UIKit.h>

@interface UIViewController (isPresentedInPopover)

@property (assign, nonatomic, getter = isPresentedInPopover) BOOL presentedInPopover;

@end

Now for the implementation - we'll be using the Objective C runtime's associated object API to provide the storage for this property. Note that a selector is a nice choice for the unique key used to store the object, as it's automatically uniqued by the compiler and highly unlikely to be used by any other client for this purpose.

// UIViewController+isPresentedInPopover.m

#import "UIViewController+isPresentedInPopover.h"
#import <objc/runtime.h>

@implementation UIViewController (isPresentedInPopover)

- (void)setPresentedInPopover:(BOOL)presentedInPopover
{
    objc_setAssociatedObject(self,
                             @selector(isPresentedInPopover),
                             [NSNumber numberWithBool:presentedInPopover],
                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (BOOL)isPresentedInPopover
{
    NSNumber *wrappedBool = objc_getAssociatedObject(self, @selector(isPresentedInPopover));
    BOOL userValue = [wrappedBool boolValue];
    return userValue ?: [[self parentViewController] isPresentedInPopover];
}

@end

So there's a convenient side effect of using this as a category - you can call up to the parentViewController and see if that is co