You can use any font in iOS app.
To use any font you need .TTF file.
You can get font file for MS song font from this link: MS Song Font
Click on Download button and you will get .ZIP file which contan .TXT and .TTF file
You can use this .ttf file with just two step
- Make configuration in info.plist to add this .ttf file
- Use That Added File in creating UIFont Object
To see how to do this two step in detail visit : Use custom fonts in iPhone App