Using gdb to print out Objective-C objects
Sometimes the object that you want to debug is more complicated then an int or string.
In those situations, you will need to ‘pass a message’ to the object:
po (int)[textField superview]
Even then, there are occasions where you will have to use a selector:
print (int)[receivedData performSelector:@selector(count) ]
And finally, use a selector with an object as an argument:
print (int)[receivedData performSelector:@selector(count) withObject:myObject ]
Reference: stackoverflow wiki