如何在Swift 4中同步执行多个自定义动画功能

I am working on an IOS App that is supposed to help people in a tourist region to make sense of means of transport. To make it crystal clear to them how to get from A to B, routes are animated with Annotation objects. For example once the user chooses to see the route from A to D, a cable car object slides from A to B. Once it finishes, a Shuttle Bus object moves along a road from B to C, followed by a boat sliding from C to D.I am working on an IOS App that is supposed to