Icons are another contender for the Metaphor Mismatch anti-pattern. People expect
familiar icons to offer specific features. Using a familiar icon in an unfamiliar way will
cause confusion.
In the top right of the Weight Watcher’s app there is the iOSsendButton. It normally
offers options like Send email, Send to Facebook. I was surprised to see Favorites and
Add to Shopping List options listed here. Offering a standard toolbar would make this
application more intuitive, and probably result in higher adoption of the “favorite” and
“shopping list” features.