Cocos2D Draw Order

In summary:

• If within same parent and same Z order, then nodes that are added first will be drawn first, followed by the ones added later in sequence.
• If within the same parent and different Z order, then it's according to Z order. The higher the Z order, the later it will be drawn. Note: negative Z order will be drawn before the parent, and positive Z order will be drawn after the parent.
• If different parents, then the Z order of the parent decides first, then Z order within each parent.
• The only way for nodes with different parents to be ordered with each other independently of parent is using VertexZ. (However, I could not get it to work with Cocos2D-X Isometric tile maps across map layers. I ended up removing all the objects (e.g. buildings) on the other layers in runtime and re-inserting them in the same layer as the other sprites as sprites, and then ordering via Z order.

Reference: http://www.learn-cocos2d.com/files/cocos2d-essential-reference-sample/Influencing_the_Draw_Order.html