Why does my menu doesn't works on Apple smartphones while it is working on Android devices? (Website related)

Created a menu at my website, but while it is working properly on Android devices (clicking a small image opens a whole menu, the basic/known system), it is not working at all on iPhones. Is there a reason for that? I could show my code, but I do not think that it could explain these differences between iOS and Android.

Would be grateful for an answer from someone who understands this.