Today I started APP KeyboardExtension and I was almost done. I found that the console was printing Could not load IOSurface for time string. Rendering locally instead.Google and Stack Overflow all the time, but there was no answer. Does anyone know the reason? Comments are welcome!

So what is IOSurface?

The IOSurface framework provides a frame buffer object suitable for sharing across process boundaries. It is often used to allow applications to move complex images, decompress and draw logic into a separate process to enhance security.

Solution

Someone on Stackoverflow asked the same question. At present, a person has given a solution, the following is his method;
Select target -> General -> select Devices with Universal and select Main Interface for iPhone & iPad.