This article is only have direct link to Embarcadero's docwiki and some comments that I think is important.
Maybe help for people who have troubles in recompile between different versions.
What's New in Rad Studio XE7
What's New in Rad Studio XE6
What's New in Rad Studio XE7
What's New in Rad Studio XE6
Conditional compilation (Delphi XE5)
for example:
{$IF Defined(IOS) }
// Code for both iOS Device and iOS Simulator.
{$ENDIF}
{$IF Defined(IOS) and Defined(CPUARM) }
// Code for iOS Device only.
{$ENDIF}
{$IF Defined(IOS) and Defined(CPUX86) }
// Code for iOS Simulator only.
{$ENDIF}
{$IF Defined(MSWINDOWS)}
{$ENDIF}
Migrating Delphi Code to Mobile from Desktop
watch out the string type and usage have some change!