UIApplication does not send notificaiton wether status bar is hidden or not. This class does!

IVYApplication.h

#import <UIKit/UIKit.h>

extern NSString * const UIApplicationDidHideStatusBarNotification;

@interface IVYApplication : UIApplication

@end

IVYApplication.m

#import "IVYApplication.h"

NSString * const UIApplicationDidHideStatusBarNotification = @"UIApplicationDidHideStatusBarNotification";

@interface IVYApplication ()

@property (nonatomic, assign) BOOL isCheckingStatusBarDisplayChange;

@end

@implementation IVYApplication

- (id)init
{
    self = [super init];
    if (self)
    {
    }
    return self;
}

- (void)setStatusBarStyle:(UIStatusBarStyle)statusBarStyle
{
    [self checkForStatusBarChangeBeforeAndAfterBlock:^{
        [super setStatusBarStyle:statusBarStyle];
    }];
}

- (void)setStatusBarStyle:(UIStatusBarStyle)statusBarStyle animated:(BOOL)animated
{
    [self checkForStatusBarChangeBeforeAndAfterBlock:^{
        [super setStatusBarStyle:statusBarStyle animated:animated];
    }];
}

- (void)setStatusBarHidden:(BOOL)statusBarHidden
{
    [self checkForStatusBarChangeBeforeAndAfterBlock:^{
        [super setStatusBarHidden:statusBarHidden];
    }];
}

- (void)setStatusBarHidden:(BOOL)hidden animated:(BOOL)animated
{
    [self checkForStatusBarChangeBeforeAndAfterBlock:^{
        [super setStatusBarHidden:hidden animated:animated];
    }];
}

- (void)setStatusBarHidden:(BOOL)hidden withAnimation:(UIStatusBarAnimation)animation
{
    [self checkForStatusBarChangeBeforeAndAfterBlock:^{
        [super setStatusBarHidden:hidden withAnimation:animation];
    }];
}

- (void)checkForStatusBarChangeBeforeAndAfterBlock:(dispatch_block_t)block
{
    if(self.isCheckingStatusBarDisplayChange)
    {
        return;
    }
    
    self.isCheckingStatusBarDisplayChange = YES;
    BOOL wasHidden = self.statusBarHidden;
    block();
    BOOL isHidden = self.statusBarHidden;
    self.isCheckingStatusBarDisplayChange = NO;
    
    if(wasHidden != isHidden)
    {
        [self postStatusBarHideStatusNotification];
    }
}

- (void)postStatusBarHideStatusNotification
{
    NSNotification *notifaction = [NSNotification notificationWithName:UIApplicationDidHideStatusBarNotification object:self];
    [[NSNotificationCenter defaultCenter] postNotification:notifaction];
}

@end

main.m

#import <UIKit/UIKit.h>
#import "IVYApplication.h"
#import "IVYAppDelegate.h"

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv,
                                 NSStringFromClass([IVYApplication class]),
                                 NSStringFromClass([IVYAppDelegate class]));
    }
}

This only works for explicit calls to setStatusBarHidden, etc. It does not get fired for the UIViewController childViewControllerForStatusBarHidden mechanism of hiding the status bar.

@slangley Didn't think of that. Thanks for the feedback!