The Xcode debugger is very powerful and in some cases seemingly arcane if you are unfamiliar with it. But there are a few very useful things you should use it for. Set a breakpoint by clicking in the gutter along the desired line of code. When code execution pauses at the breakpoint, and you see the debugger prompt appear (lldb), you can type various commands into it. These 2 are very handy and easy to use:
po <expression evaluating to an object> print <expression evaluating to a native type>
po [[obj someFunction] anotherFunction] print i*3
Sometimes you may need to cast to the correct return type to work, e.g.
Type help to see more details.