In an effort to distance itself further from its rival, and to enjoy the benefits of building its own in-house software, Apple replaced Google Maps in iOS 6 with its own mapping solution. And it’s been taking criticism over the switch ever since.

But iOS 6 Maps isn’t just negatively impacting Apple. It’s also substantially eating into Google’s mobile maps marketshare around the globe. According to a new report, Google Maps marketshare declined by nearly 50% in China last quarter…

Macworld points to an investors note from Analysys International:

“Google’s mobile maps product saw its market share in China decline by close to 50 percent in the third quarter due to Apple switching to its own maps product for its iOS 6 upgrade, according to a Beijing-based research firm…

…The decline largely stems from Apple’s September upgrade to its iOS operating system, which removed Google maps and replaced it with Apple’s own mapping product for China, according to Yi Jingxue, an analyst with Analysys International.”

The stark decline isn’t all that surprising, given that as of October 22nd, an estimated 2 out of every 3 Apple devices had updated to iOS 6. It just goes to show you how important iOS was to Google’s mobile mapping business.

Google could gain at least some of that marketshare back if it produced a compelling standalone iOS app. There’s been a lot of talk recently that such an app is in the works, but there’s also uncertainty on whether or not Apple would approve it.

Though it took a lot of heat over its own Maps app early on, the complaints have calmed down a bit as Apple continues to update its database with new locations and better directions. And we’re also expecting improvements in iOS 6.1.