How to display a progress bar during loading another table view with a table view

I have a table view cell , during click it , another table view will open , you can select something as the value of the table view cell. The issue here is the data in the second table view is big and it will take long time to load. So after I click the cell , the screen will froze there which is not user friendly. I want to displaying a progress bar during load the second table view. But I can not find a good place to add that. I am wondering in which method should I add the code to display the progress bar.

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