Typing on Apple's devices has become a lot easier with iOS 8, but Apple's QuickType keyboard is not the only reason why.

A number of popular Android keyboard apps have made their way over to the Apple App Store, with the top three paid and top two free apps on the App Store being keyboard apps at the time of this writing.

SwiftKey has quickly become the most popular keyboard app on the app store, and has also long been a popular keyboard app on Android device. In fact, the SwiftKey app on iOS 8 hit a million downloads in only 24 hours.

"Obviously we're overwhelmed that SwiftKey Keyboard shot to the top of the charts after launching on iOS 8," said SwiftKey Chief Marketing Officer Joe Braidwood. "We've worked really hard on getting something ready for launch and this is the ultimate reward."

There are a number of reasons why SwiftKey has become so popular. The app is a predictive typing app, so basically it will display a list of suggested words, which users can simply tap to complete the word, without having to type the rest of it. As users continue to use the app, it continues to learn the users style and becomes better at predicting what the user types.

While the app is certainly easy to use, it also requires full access, which is a deal breaker for many users. Full access gives SwiftKey permission to keep track of the users typing history, which may include things like credit card numbers and so on. While this may seem scary, it really is only so the app can better predict what the user is typing. Of course, users can still opt to use the keyboard without enabling full access.

While the new keyboard on iOS does offer suggestions as the user types, SwiftKey has a few tricks up its sleeve that the iOS 8 keyboard doesn't have, such as the ability to type by swiping characters across the keyboard rather than tapping on them.

SwiftKey isn't the only popular keyboard app on the App Store right now. Another popular app is Swype, which costs 99 cents, and is one of the best gesture based keyboard available. It allows users to enter symbols, punctuation and capital letters with gestures. Like SwiftKey, it also allows users to choose from a list of predicted words as they type.

There are many other keyboard apps flooding the App Store and this is likely to continue because of the fact that this is the first time that Apple is allowing third party keyboards on the App Store.