The way a lot of company’s handle these is to try and work out a licensing arrangement when they discover infringement.
If the other party refuses to accept a licensing agreement then a lawsuit is used to force them to the table.
Although Apple is doing well in Nokia’s market, nokia still has market share. using the courts is one way to maintain or get your market share. Apple did the same thing to stop that mac clone company.
I have had two Nokia phones and will never own another. In fact, after getting my iPhone, I have decided it is a total game changer and have no intention of ever switching again.
The thing just cannot be any easier to use. Nokia was always a pain and never delivered what it promised.
Apples to oranges. Apple sued Psystar because Psystar blatantly violated the licensing agreement in every copy of OS X they distributed.
The only way your statement would hold water is if Apple purchased software from Nokia, then copied it freely, and used it on their own hardware in direct violation of copyright and patent.