如何将用户的当前位置与其他位置进行比较，并将其显示在可选择的视图中?

I am developing an app in swift and I have to compare user's current location to the other locations taken from a JSON file. Then I have to display all of the locations which are in a certain range from the user's location. This range I take from a UISlider. I mean when the user selects 25km in the slider, the app has to determine the current user's location and display all of the fruits which are in this range.I am developing an app in swift and I have to c