First could you please check that the ATKCore.framework is the last framework to be linked in your project?
We have noticed on our side that an error may also occur if the MathView is 'nil' in your Xcode project, so please check as mentioned in our documentation that the MathView exists in your StoryBoard and has the 'reference outlet' to the View Controller, please visit Apple Developer website for more details: http://help.apple.com/xcode/mac/8.3/#/dev31645f17f
Please let know if it helps.
Placing the ATKCore.framework as the last framework fixed the problem.
Thanks for the feedback!