Undo/Redo for drawing in iOS

I have found a solution for this, we need to create a array of array of DrawingPaths:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
   // Do the above code, then
   [m_undoArray addObject:self.currentPath];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
   [m_parentUndoArray addObject:[NSArray arrayWithArray:m_undoArray]];
}

and then stroke the path in DrawRect.