debug: Obtain a list of all instance variables of an object (unknown type)

Exploiting the code of the accepted answer of the question that you linked, the only thing that you need to do is to wrap it into a convenient method, so that you could call it at any time during debug. At your place I would write a category extending NSObject, adding a method that returns a NSDictionary with all the ivars; Here is an example:

- (NSDictionary*) ivars
{
    NSMutableDictionary* ivarsDict=[NSMutableDictionary new];
    unsigned int count;
    Ivar* ivars=class_copyIvarList([self class], &count);
    for(int i=0; i<count; i++)
    {
        Ivar ivar= ivars[i];
        const char* name = ivar_getName(ivar);
        const char* typeEncoding = ivar_getTypeEncoding(ivar);
        [ivarsDict setObject: [NSString stringWithFormat: @"%s",typeEncoding] forKey: [NSString stringWithFormat: @"%s",name]];
    }
    free(ivars);
    return ivarsDict;
}

Then given that object of which you don't know the type, if it directly or indirectly inherits from NSObject you just need to print the dictionary returned from this method:

(lldb) po [someObject ivars]

Credits: How do I list all fields of an object in Objective-C?

PS: You need to import objc/runtime.h .

Since you are using lldb, you may want to try

_ivarDescription
_propertyDescription
_methodDescription
_shortMethodDescription

You can use them with po when you hit a breakpoint

po [yourObject _ivarDescription]