Android M is now 'Android 6.0 Marshmallow'
Google has just released the third and final version of the Android M Developer Preview, along with the Android 6.0 SDK. The company has also confirmed that Android M is the Android 6.0 Marshmallow and to prepare for it, the company will be opening up Google Play for apps that can handle the API level 23 found in Android Marshmallow.
Not much detail has been given out by Google developers and no specifics have been mentioned yet. All that is known is that the Android 6.0 Marshmallow might be released around the end of September or the start of October, in line with the rollout of Google Nexus 5 (2015) from both LG and Huawei.
Some of the changes that were made concern the Android platform and the API. For the Android platform, Google updated the final permissions user interface and made sure that the permissions performed better. For the API, they made some changes to the fingerpint API thus allowing for better fingerprint capturing and making the process more reliable. Google also says that at the consumer launch this fall, the Google Play store will also be updated so that the app install and update process supports the new permissions model for apps using API 23.
Google developers have given specific instructions to get your apps ready for Android Marshmallow. According to the Android Developer Blog, "The final Android 6.0 SDK is now available to download via the SDK Manager in Android Studio. With the Android 6.0 SDK you have access to the final Android APIs and the latest build tools so that you can target API 23. Once you have downloaded the Android 6.0 SDK into Android Studio, update your app project 'compileSdkVersion' to 23 and you are ready to test your app with the new platform. You can also update your app to 'targetSdkVersion' to 23 test out API 23 specific features like auto-backup and app permissions".
You can use Google Play's newly improved beta testing feature to get early feedback and to monitor if your updated app runs well on Android Marshmallow and older versions.