In the previous article we created some commands an ran them through the system.

In this article I will show how easy it is to make these events wait for each other to complete.
Read more about The command pattern - using it on deferred objects in javascript (1 minute)

So in previous article I showed some examples of the command pattern, now I will detail a simple application.

Firstly let’s create a simple bit of HTML to help us visualise what we are doing.
Read more about The command pattern - an example in javascript (2 minutes)

When dealing with the command pattern, we have to identify an invoker object.

This object will process our concrete commands and store a list of events that have been applied. What does this invoker object look like. I identified the following interface. Firstly we know we want the ability to “undo” and “redo”.
Read more about The command pattern - invoker object (1 minute)

I was uploading a release for an app tonight, but I got a warning on the submission process explaining that I was missing a recommended icon 120x120 pixels.

I thought this should be an easy thing to fix, all I need to do is drop in another icon. Firstly I open the Images.xcassets file to investigate…
Read more about The boy scout rule - Leave the Campground Cleaner then when you found it (1 minute)

In the last post I introduced the command pattern and showed an example of a command object. In this post I am going into more detail on the concrete command objects and showing how it’s important to design the arguments up front so that you can use one command for both redo and undo events.

Firstly I will list out all the basic commands I identified in the app that a user can perform.
Read more about The Command Pattern - the concrete command objects (2 minutes)