Actually I have a table view with options, but alongside I have a complicated scroll design. How could I go about implementing this scroller?

Actually I have a table view with options, but alongside I have a complicated scroll design. How could I go about implementing this scroller?

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You could probably use a customized UISlider for this. When the value of the slider changes, you can adjust the scroll offset of the UITableView next to it.
I wonder whether it is really necessary for your design to use this kind of element since it is not very intuitive (at least on iOS) to use a custom scrollbar. When you really have to use the custom scrollbar, I would go with a customized version of an UISlider.
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UISliderverticalSlider change method