Prototyping at the command line

Here’s a quick tip that comes in really handy for me all the time. When you are working on a complex algorithm or any other compartmentalized bit of code, try using a little command line program to work out the code. This isolates you from all of the overhead and complexity of building iOS GUI type applications and helps you focus on the essence of what you are trying to accomplish. It’s also helpful when you are not sure about what a certain class can do or you need to figure out how some method works.

Here’s how to set up a quick and dirty command line program:

Start up Xcode and from the File menu select New > New Project ….
In the dialog, select, “Application” under the Mac OS X section on the left hand side. Then, in the right pane, select, “Command Line Tool” and click Next.



Type the name of your project into the Product Name text box. Select “Foundation” in the Type drop-down box. The Foundation project type tells Xcode that you will be working in Objective-C and that you want to use the Cocoa Foundation framework. Click Next.



You will be prompted for a location to save your program. Pick a location that you will remember. I usually just throw these one off type of projects on to the desktop. Also, uncheck the “Create local git repository for this project” checkbox. You don’t need source control for one off prototype projects. Finally, click Create and your new project will be created.

Now, open up main.m and put any code that you want to test in the main function where the template has the NSLog “Hello World!” statement. You can use NSLog or printf to print to the output console. You can use scanf to get user input from the console.

I hope that you try this technique out. Good luck!