Tools
Typing code into Xcode and hitting the Run button to see if it works is only a part of the story (though undoubtedly the most central part). There are a number of other tools that you should consider an essential part of your toolbox and countless others that may be of immeasurable help to you, once you have found them (often easier said than done) and learned what they can do for you.
What follows is a brief look at some of the most important tools already at your disposal (in that they are already installed on your machine), some further utilities that are free to use, and one or two paid apps that are at least worth checking out and are not expensive to license should you find them useful.
Terminal
In case you have not met it before, Terminal is a Unix console (Unix is the basis of OS X) and is installed along with the operating system. It is an important tool in many ways, though its value really first becomes apparent after you have become familiar with using it.
The Unix commands...