Doesn't mean Apple will use it
You seem to have the old-fashioned idea that people patent novel features of their products. That's not how the patent system works nowadays.
Apple will have some R&D engineers working on phones. Part of their job will be to come up with patentable ideas. They likely get a bonus for each patent filed (around five hundred quid per patent is the typical ballpark). Whether Apple use the idea or not is irrelevant - they still get their bonus, and it still looks good on their performance review.
The easy way to come up with patents is to take existing tech and apply it to a new field. E.g. it's interchangeable lenses... but on a phone! The "but on a phone" bit lets you get the patent past the patent office. It may be obvious, but if no-one has written down how to do it then the patent office don't consider it "obvious", and they grant the patent. If you get half a dozen smart people together to brainstorm you can sometimes come up with a half a dozen patent ideas in an hour.
Why do big companies want lots of patents they're not using? Very simple: licensing depends on volume of patents. If Apple have 100 decent patents on SmallCo's phone, and SmallCo has no patents on Apple's phones, then SmallCo are toast - one of those patents is likely to stick, so SmallCo have to pay up or get out of the market. If Apple have 100 decent patents on BigCo phones, but BigCo have 100 decent patents on Apple phones, then suing would be suicidal for both companies and they are forced to cross-license. When it gets down to 5 or 10 patents a side, both sides will be tempted to take it to court and see if they can invalidate the other's patents (see: Apple V Samsung).
Source: I worked in R&D for a big company so I am an "inventor" on some patents.