Disabling slider while the collection view reloads

My app uses a collection view to display a list of news articles. The topics can be adjusted with a slider on the top of the screen.
If the user changes the value of the slider, the collection view immediately loads, and while the view updates, the slider becomes unresponsive. This leads to a glitchy UI while navigating the app.
How do I resolve this issue?
I thought of disabling the slider while the view reloads, but there is no way to determine that the collection view is reloading.
Any help regarding this is highly appreciated.
Thank you!

This is better asked over at the Apple Developer forums, or another Apple-specific site. Your question is not about Swift the language, rather it's about Apple's private UI frameworks, which are not the subject of these forums.