问题
I'm running into a problem with the size of my pickers when I put them inside of a stack view. The pickers change their size to their default size when they are put into the stack view. They do not do this when they are not placed into the stack view
回答1:
Just add height and width constraints to your picker before you add it to your stackview and that should solve your problem.
来源：https://stackoverflow.com/questions/32854074/issues-with-uipickerview-inside-a-stackview