|Thanks to the close collaboration between the stm32duino community and ST, Arduino™ IDE brings simplicity to the STM32 ecosystem of developers.|
Indeed Arduino software libraries have been ported on top of the STM32 Cube software drivers to enable Arduino developers to take direct benefit from any STM32 mcu (see www.stm32duino.com).
The Arduino™ IDE can simply be configured to support boards from each STM32 mcu serie : to help you get started with the Arduino™ IDE on STM32, follow the "Getting Started" wiki (stm32duino wiki: https://github.com/stm32duino/wiki/wiki).
Only one package to support all STM32 mcu series. See the Latest release to follow the core development.
Non exhaustive list of proposed targets:
Full list is available here: GitHub - stm32duino - boards available
Compatibility of the core has been extended and allows to benefit of more Arduino Libraries. See Libraries · stm32duino/wiki for further information.
STM32 libraries have been developed to support dedicated hardware features and X-NUCLEO :
So have a look here to see which one are available or thanks the Arduino "Library Manager" using "stm32" to filter your search.
You can find in attachment of this blog post the presentation of the STM32duino workshop done by parata.carlo in Maker Faire Rome 2017. It shows how to start to play with NUCLEO and X-NUCLEO libraries in the Arduino™ IDE.