Why did Android application design immerge and spread rapidly all of the sudden?

For a considerable time, iOS was the only platform every body cared about. There was a big number of users and it had its own audience. However a few years ago, another player entered the same market. Android growth has been rapid and it spread very quickly and could no longer be ignored by application builders. Businesses started seeing android as a big and profitable market and started investing in it. Although, Android platform can appeared intimidating to the new users, there is a lot of information online available for it.

in my opinion the most important thing that growth was depending on were the prices of devices. When apple high-end smart phones are expensive, they can be found an "no name" brands with android OS in it. Although I do not recommend buying this cheap Android phones without earlier knowing technical specs of it.

Some of them are crap just like chinesee "Sciphone" "Allphone" or "iPhne" and for sure many more

As Android is promoted by Google, people or smart phone users trusts more on such mobile platform. From the developer’s point of view, Android is an open-source mobile platform so most of the developers wish to go for Android and it becomes easy for them to go for its application development process. In addition, android smartphones users are always eager to use diverse applications in their android device. Smart phone users can get a wide range of Android based smartphones in the mobile market as compared to other mobile platforms.