47.9 Relevance

As previously mentioned, iOS allows widgets to be placed in a stack in which only the uppermost widget is visible. While the user can scroll through the stacked widgets to decide which is to occupy the topmost position, this presents the risk that an important update may not be seen by the user in time to act on the information.

To address this issue, WidgetKit is allowed to move a widget to the top of the stack if the information it contains is considered to be of relevance to the user. This decision is based on a variety of factors such as previous behavior of the user (for example checking a bus schedule widget at the same time every day) together with a relevance score assigned by the widget to a particular timeline entry.

Relevance is declared using a TimelineEntryRelevance structure. This contains a relevancy score and a time duration for which the entry is relevant. The score can be any floating point value and is measured relative to all other timeline...