UXTableDataSource

UXTableDataSource is what a UXTableView asks for its contents. The contract is two methods.

#use <UXKit>            // or #import "UXTableView.xc"

Overview

protocol UXTableDataSource {
    i32 numberOfRows(UXTableView* t);
    u8* valueForCell(UXTableView* t, i32 row, i32 col);
}

The table never holds your data. It asks every time it draws. Your model stays in whatever shape suits it, and the table is a view of it, not a second copy that can drift out of step.

class Library : Object <UXTableDataSource>
{
    Array<Track>* tracks;

    i32 numberOfRows(UXTableView* t) { return (i32)tracks.count(); }

    u8* valueForCell(UXTableView* t, i32 row, i32 col) {
        Track* tr = (Track* ?)tracks.get((u16)row);
        if (col == 0) { return tr.name; }
        if (col == 1) { return tr.artist; }
        return self.formatMinutes(tr.mins);
    }
}

Topics

numberOfRows · valueForCell

numberOfRows

i32 numberOfRows(UXTableView* t)

How many rows there are now. The table calls this whenever it needs the count, so return tracks.count() directly. There is nothing to cache or invalidate.

The table is passed in, so one object can be the data source for several tables and tell them apart by identity.

valueForCell

u8* valueForCell(UXTableView* t, i32 row, i32 col)

The text for one cell.

A cell returns text. If your model holds a number, a date or an enum, it becomes a string here. Formatting (locale, padding, units) stays in your code, so a column of minutes looks the way you chose.

Mind the buffer you return. Returning a pointer into a scratch buffer is fine, but the table may ask for several cells before drawing any of them. If a formatted value has to survive that, store it. Formatting and returning immediately is safe.

col indexes the columns you added with addColumn, which carry only a title and a width. A column does not know what it holds, so reordering columns is a layout change and nothing in your model moves.

Changing the data

tracks.add(Track.make((u8*)"Ochre", (u8*)"Mirrer", 5));
table.reloadData();

Change the model, then tell the view. reloadData makes the table ask again; there is no snapshot to keep in step.