What is iOS 9.3 system font name?
iOS 9 uses SanFranciscoUIDisplay and SanFranciscoText as their default font.
SanFranciscoUIDisplay is used for titles and larger font wheres SanFranciscoText is used for paragraph text and smaller font.
They are the System Font in Xcode or you can download them here (but you need a developer account):
You can use the default font like this:
Swift 2:
UIFont.systemFontOfSize(15)Swift 3 and Swift 4:
UIFont.systemFont(ofSize: 15)