Multi-selection is the act of selecting a set of elements in a graphical user interface in order to perform an operation on that set. Examples of multi-selection are selecting thumbnails in an image gallery or files on a file explorer. Whether and how multi-selection is supported in different applications varies widely, which leaves user experiences wanting. Järvi and Parent recently introduced an abstract model of multi-selection that helps programmers to implement multi-selection uniformly and correctly in desktop GUIs. This paper adapts the model to touch-screen devices. We present the rationale for choosing particular gestures for selection commands and explain how they map to the original model. A user study comparing our selection model with the established multi-selection features used by major Android and iOS applications shows that our selection feature allows for the fastest and most accurate selection
