Play Live Loops cells in GarageBand for iPhone
You can start and stop playback of cells in the grid individually, start cells in a column simultaneously, and start playback of selected cells simultaneously regardless of their position in the grid.
Tap a cell to select it.
When cell editing is turned on, you can select multiple cells for editing. You can select and edit multiple cells in the same row, but only one cell in a row can play at a time.
Start or stop playback: Tap a cell.
Start playback of all selected cells: Tap a selected cell.
Start all the cells in the column: Tap the trigger below a column.
Stop playback of a cell: Tap a playing cell or tap an empty cell in the same row as the one playing.
Stop playback of all selected cells: Tap a selected cell to stop playback of all selected cells.
Stop playback of all cells in the grid: Tap the trigger below an empty column.