I have an Android phone, no iPhone. As far as I know there is no way to hide which apps you have downloaded, although you can "lock" your phone so that other people cannot have access to it.
I usually suggest that if you are concerned about whether or not someone else will look at your phone and see that you have a gay cruise app, you should use a mobile web site instead. We recommend Men4SexNow
Signup | Gay Hookup Site | No Strings Attached Gay Sex | NSA Gay which is one of the longtime advertisers on CRUISING for SEX, since using them helps keep our web site free for you. Manplay is another one of our advertisers that has a mobile site, and you'll see their banner ads here, too.
One of the advantages of using a mobile web site is that you can also either (a) clear your browser history; or (b) visit the web site in an "incognito" or "private" window, which means (among other things) that the browser doesn't have an easily accessible record of your history.
It's true that the mobile web sites may not have all the features of the apps, although I believe that can show you guys online near you. It's a trade-off, really, between versatility and privacy and it's really up to you.