15.4.4.2 The Print Command With Objective-C

The print command has also been extended to accept methods. For example:

print -[object hash]

will tell GDB to send the hash message to object and print the result. Also, an additional command has been added, print-object or po for short, which is meant to print the description of an object. However, this command may only work with certain Objective-C libraries that have a particular hook function, _NSPrintForDebugger, defined.