Xcode custom font not showing in app

I have downloaded Open Sans font and added all the .tff files into my Xcode project, and have checked the checkbox in "Target Membership" pane for each file. I have added the UIAppFonts key and values in Info.plist, and I am sure that the values are typo-free. Plus, the .tff files are added to "Copy Bundle Resources", and the custom font is showing up in Interface Builder. And then I changed the font of all the labels to Open Sans in the Interface Builder (no code).

But when I run the app in the simulator, all the labels and buttons are showing the system font in ultra small sizes, like this:

One thing to note is that I am using Xcode 7 beta 5, and the app's Base SDK is iOS 9.

But why is there this problem? Is it a bug? Thanks!

Check That fonts inside the proyect are part of the target. Select fonts, verify the property Target Membership for your app is checked at the right in File Inspector.

That solved the problem for me: