Since iOS 6 was released there's been no doubt which of its many features has garnered the most negative feedback. Apple's decision to jetison Google Maps in favour of its own service has been met almost unanimously with derision.

However, it has since come to light that not only did Apple still have one year left on its contract with Google, but that the Cupertino company may not have had any other option.

Sources claim Apple wanted to add voice-guided turn-by-turn navigation to its iPhone and iPad maps service, because that would be of far more use to drivers than a merely visual one. However, although that feature is resident in the Android version of Google Maps, Google itself didn't want to hand over the data required to enact the same feature in its rival's devices.

It's not all Google's doing, though, as the sources also told AllThingsD that Apple refused Google more say in how the iOS mapping functionality was implemented. It wasn't happy at being just a data provider and wanted to add extra features of its own to "Maps", such as Google Latitude.

Apple turned this down, says AllThingsD, because it was wary of including Google branding embedded into its own software.

"There were a number of issues inflaming negotiations, but voice navigation was the biggest," said one source familiar with the matter. "Ultimately, it was a deal-breaker."

It is believed that Google is now working feverishly on its own iOS Google Maps app, which many applaud. However, it won't be afforded the same integration throughout the operating system as before. Other map-dependent applications, such as running and geotagging apps, will more than likely be limited to using Apple Maps.