SearchDelegate<T> class abstract

Delegate for showSearch to define the content of the search page.

The search page always shows an AppBar at the top where users can enter their search queries. The buttons shown before and after the search query text field can be customized via SearchDelegate.buildLeading and SearchDelegate.buildActions. Additionally, a widget can be placed across the bottom of the AppBar via SearchDelegate.buildBottom.

The body below the AppBar can either show suggested queries (returned by SearchDelegate.buildSuggestions) or - once the user submits a search - the results of the search as returned by SearchDelegate.buildResults.

SearchDelegate.query always contains the current query entered by the user and should be used to build the suggestions and results.

The results can be brought on screen by calling SearchDelegate.showResults and you can go back to showing the suggestions by calling SearchDelegate.showSuggestions.

Once the user has selected a search result, SearchDelegate.close should be called to remove the search page from the top of the navigation stack and to notify the caller of showSearch about the selected search result.

A given SearchDelegate can only be associated with one active showSearch call. Call SearchDelegate.close before re-using the same delegate instance for another showSearch call.

Handling emojis and other complex characters

It's important to always use characters when dealing with user input text that may contain complex characters. This will ensure that extended grapheme clusters and surrogate pairs are treated as single characters, as they appear to the user.

For example, when finding the length of some user input, use string.characters.length. Do NOT use string.length or even string.runes.length. For the complex character "👨‍👩‍👦", this appears to the user as a single character, and string.characters.length intuitively returns 1. On the other hand, string.length returns 8, and string.runes.length returns 5!