I have heard, rightly or wrongly, that apps have to be written specifically with Android Runtime in mind in order for the bytecode to be changed into native machine code on a given device. Is this true? If so, how can I do that?
I know similar questions have been asked, but all the questions I have found were NDK related and this is not.
There should be no need to write apps with this thing in mind, given the fact that the most important thing that changes is the way the apps are compiled.
On Android versions prior to KitKat, apps run with the "classical" Just-in-Time compiling scheme, that is, the code gets compiled as it runs (in simple terms). The difference with ART is that ART uses the so-called Ahead-of-Time compilation. This means that your same code gets pre-compiled before it actually runs on the device.
A very simple, but more technical, comparison can be found here.
I wouldn't worry much about it if I were you, because, except for those willing to dive into native code, most programmers write their code on top of all the layers of the classical app architecture; even should the runtime/compilation/etc change, that should not affect the way top-level code is written. And those willing to dive into native code will be able to do that in post-KitKat age as well.
