I have the following code in my C++/Objective-C app:

#import <YandexMobileAds/YandexMobileAds-Swift.h>

@class AdHook;

namespace MyApp
{
    class AdHolder
    {
    public:

        AdHolder(IosInterstitialAd* cpp_ad);

        AdHook* m_hook;
    };
}

using namespace MyApp;

@interface AdHook : NSObject <YMAInterstitialAdLoaderDelegate, YMAInterstitialAdDelegate>
{
    @public IosInterstitialAd* m_cppAd;

    @public YMAInterstitialAdLoader* m_loader;
    @public YMAInterstitialAd* m_interstitialAd;
}
@end

@implementation AdHook 

- (id)initFromCpp:(IosInterstitialAd *)cpp_ad
{
    if (self = [super init])
    {
        m_cppAd = cpp_ad;
        m_interstitialAd = nil;

        m_loader = [[YMAInterstitialAdLoader alloc]init];
        m_loader.delegate = self;
    }
    return self;
}

AdHolder::AdHolder(IosInterstitialAd* cpp_ad)
{
    [YMAMobileAds enableLogging];

    m_hook = [[AdHook alloc]initFromCpp:cpp_ad];
}

void SomeOtherClass::load()
{
    NSLog(@"IosInterstitialAd::load()");

    YMAAdRequestConfiguration* configuration = [[YMAAdRequestConfiguration alloc]initWithAdUnitID:@"demo-interstitial-yandex"];

    [m_holder->m_hook->m_loader loadAdWithRequestConfiguration:configuration];
}

I create an instance of AdHolder class in C++ code and AdHolder‘s constructor creates an instance of Objective-C class AdHook that in its turn crates its internal Objective-C objects.

But I do not understand well enough what is the lifetime of m_hook? And I suspect that it is deleted at some point, because when I try to access m_hook->m_interstitialAd from YMAInterstitialAdLoaderDelegate callback I get a wrong value and the app crashes.

Is m_hook a strong reference? If it is not how to make it strong?

EDIT1

Tried to randomly add retain call to various objects in my app and made the app work by adding retain call to AdHook::m_interstitialAd:

- (void)interstitialAdLoader:(YMAInterstitialAdLoader * _Nonnull)adLoader didLoad:(YMAInterstitialAd * _Nonnull)interstitialAd
{
    NSLog(@"IosInterstitialAd::YMAInterstitialAdLoader::didLoad, %@", interstitialAd);

    m_interstitialAd = [interstitialAd retain];
    m_interstitialAd.delegate = self;
}

at least my app stopped crashing when I access m_interstitialAd.

So the question probably is if AdHook::m_interstitialAd a strong reference?