You can use the XCTest to test your classes.
You can find all the information you need in the Apple documentation is actually pretty easy to use.
https://developer.apple.com/Library/ios/documentation/DeveloperTools/Conceptual/testing_with_xcode/testing_2_testing_basics/testing_2_testing_basics.html#//apple_ref/doc/uid/TP40014132-CH3-SW1
If you want you can check this tutorial as well.
http://rshankar.com/test-driven-development-in-ios-beginners-tutorial-part-1/
If you want you can set break points as well and check that your code is executing properly. Sometimes when I just want to proof-test small classes I do it just setting a couple of break points instead of the XCTest classes but it all depends on your study case. If you have a decent amount of classes I would suggest to use XCTest to check that the classes are actually doing what is expected setting your assertions and the other conditions that XCTest offers as a framework.
Another way you can do your testing if applicable is using NSLog to print in console lines or values of interest at each stage of your code execution.
You mentioned the command line. If you set breakpoints you can use po objName to print the value or print varName to check values of objects and primitive variables correspondingly. po stands for print object and print well... There's different options if you feel comfortable using the console just set NSLogs at certain point of your code or set the break points and print the values using po or print commands in the console.
Here you can check the string format specifiers for NSLog which are the same ones used for NSString
https://developer.apple.com/library/ios/documentation/cocoa/conceptual/Strings/Articles/formatSpecifiers.html
