While trying out watchKit and watchOS, for the first time, to make a small app, I have this issue. I cannot fit 2 WKInterfacePicker objects beside each other. Eventhough I made them narrow enough, it doesn't seem to fit. They always come back one on top of the other. I did not find any way to include 2 components in the picker either. What is the secret?
Here is the secret I found to solve my problem, I hope it may help someone else who may have the same issue.
Inside Interface.storyboard, there is a component called Group. If you use it you will be able to put the pickers, side by side, inside it.
At the time I am writing I have only tried 2 WKInterfacePicker objects, and only in the simulator.