Do you know if I can use San Francisco Mono font in my app?
I can find the font in Xcode folder and it works fine, but I don't know if Apple allows to use it.
This is not allowed. From the terms of service:
This SF Mono Font (the “Apple Font”) is licensed to you by Apple Inc. (“Apple”) in consideration of your agreement to the following terms. If you do not agree with these terms, do not use the Apple Font.
You may use the Apple Font solely in conjunction with Apple-branded applications, including, but not limited to, Xcode, Terminal.app and Console.app. You may not embed or use the Apple Font in or with any other software applications or programs or other products and you may not use the Apple Font to create, develop, display or otherwise distribute any content, documentation, artwork or any other work product.