The user has to select from a pool of items or options. Order or sequence of the items may have some relevance to the user.
The choice of proper solution is influenced by the frequency of actually changing the selection.
[Small wireframes of picker and two-lists]
Ask yourself whether the selection of items will regularly be displayed without the need to change it or if the selection is likely going to be changed most of the time it is displayed
* In the first case, use the ((Picker dialog)). * In the second case, use the ((Two Lists with Arrow Buttons)).