How can I know if an annotation is already on the mapview

问题

I trying to add annotation pin to Mapview if and only if there is no such same pin already on mapview to avoid having multiple repeat annotations at the same location.

Any one can show me help?

回答1:

You can use mapView.view(for:) method.

e.g.

    if (self.mapView.view(for: annotation) != nil) {
        print("pin already on mapview")
    }

回答2:

The approach suggested by @Kosuke Ogawa would work. However it is not a good idea to rely on the UI determine application state.

For eg: You most probably have a list of annotations stored in some sort of data structure in your view controller (I am guessing an Array). This data structure should be the source of truth.

In your case, to determine if a an Annotation is already on the map, check if the Data structure that feeds the mapview contains the annotation and proceed.

来源：https://stackoverflow.com/questions/51010956/how-can-i-know-if-an-annotation-is-already-on-the-mapview