I know, I know, it's crazy to say Google (NASDAQ:GOOGL) is taking over the iPhone just as the 5c and 5s went on sale and iOS 7 made its wide debut. But it's hard to ignore Google's continuing expansion on Apple's (NASDAQ:AAPL) flagship device -- and it should make the iMaker just a bit worried.

Isn't 80% enough?!
Google's Android already claims about 80% market share of global smartphone operating systems, but over the past couple of months Google has made some big inroads on Apple's mobile operating system as well.

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Google apps available on iOS. Screenshot of iPhone 5.

Gmail, Chrome, and Google Maps obviously come to mind when you think of Google on iOS, but the image above shows just how many options Google offers Apple's users. Some apps are more used than others, of course, and others are just for businesses, but it doesn't underscore Google's presence on Apple's operating system.

Mapping new territory
It's no secret Apple and Google have fought for mapping usage on iOS. According to research from Mobida, 80% of iOS users that use Apple Maps access it weekly, compared to 55% for Google Maps. While Google takes a lower percentage, it's still extremely high considering Apple Maps comes preloaded on iOS. But Google is interested in much more than getting iPhone users to their destinations.

Just last month, the Android maker launched Google Now for iOS, bringing real-time data and predictive information to the iPhone. Those features were previously reserved for Android users, but not any more. Now iOS users can view alerts telling them when packages have been delivered, what the traffic's like getting to work, suggestions for places you may want to eat, and more. Even with Siri's iOS 7 upgrades, it still doesn't offer iOS users predictive information like Google Now.

If that weren't enough, the company just brought Google Wallet to iOS this week. Wallet allows friends to send money to each other just by using their email address; stores credit, debit, and loyalty cards; and coupon offers. Wallet also comes with 24/7 fraud monitoring and purchase protection. While it's unclear how popular Wallet will be on iOS, Apple has yet to release such a comprehensive payment app and its Passbook app only stores loyalty cards and coupons. 

But Google Now and Wallet aren't as important as the mobile browser wars. Back in December 2012, Chrome had just 10% browser market share for active iOS users, but in July of this year that share had jumped to 17.4%, according to mobile market research from Onavo. Google pays traffic acquisition costs to Apple each year -- estimated to be around $1 billion in 2014 -- to keep its position as the main search engine in Safari, so it desperately wants iOS users to switch to Chrome.

Many of Google's services are free to use, while the company makes its money off of mobile advertising. Mobile research from eMarketer estimates that more than 48% of net U.S. mobile Internet ad revenue will go to Google this year -- and will hit more than 50% by 2015.

Apple saw Google's app popularity coming a while back and ditched pre-loaded apps like Google Maps and YouTube from its iOS. But that hasn't stopped Google from growing its services and features on the operating system. As long as Google can make money from iOS users -- and it certainly can -- it will continue making great apps for the system. While Apple customers are typically a loyal bunch, they're still likely to use apps with the best usability and most features. With Google making inroads in so many areas of iOS, Apple shouldn't test the limits of that loyalty.

Fool contributor Chris Neiger has no position in any stocks mentioned. The Motley Fool recommends Apple and Google. The Motley Fool owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.