Possibly, as mentioned officially in documentation of Google Maps Android API, the below restriction regarding infowindows applies to Google Maps iOS SDK also :
Info window is not a live View, rather the view is rendered as an image onto the map. As a result, any listeners you set on the view are disregarded and you cannot distinguish between click events on various parts of the view. You are advised not to place interactive components — such as buttons, checkboxes, or text inputs — within your custom info window.
So basically clicking on any part of the infowindow will trigger only “didTapWindowOfMarker“