问题
When i create a new service, then this service will have a main datamodule (DM), and when i add this service to an already existing app, then delphi automatically add to the dpr (in the uses clauses) of this app the unit of the datamodule:
uses ...
...
myService_mainunit;
why ? it's also make after not possible to compile under IOS ...
回答1:
The IDE has absolutely no idea what your intentions are. It has no clue that you only want to use this for Android, regardless of if it's Android-specific code or not. You have to write the code which tells it this, such as using conditionals.
When you created a new Android Service, the IDE set up a pre-made template for you. This template just happens to use a Data Module to do its work. But when you add the Data Module to a project, the IDE simply does not know why you want to add it. It's just doing its job, it does this for any and every unit you add to your project, regardless of what that unit's purpose is. In fact, there is no such thing as adding a unit to your project and not being in the DPR uses.
"it's also make after not possible to compile under IOS"
Again, this is easily resolved by wrapping platform conditionals around it. Of course, the IDE "takes control" of the DPR file, so perhaps not that easily, as the IDE could malform your code. It is however very possible by not including this Data Module in your project, but place it in a location where your project can find it.
来源：https://stackoverflow.com/questions/45040463/why-when-we-add-an-android-service-to-an-app-delphi-automatically-include-in-th