This sort of scenario is a clear breach of contract, regardless of laws surrounding IP. Apple seems substantially unable or unwilling to retaliate for breach of contract against their own Chinese manufacturing partners. This is a substantial loss of control that sooner or later will come home to roost - because if this can happen to the richest company on the planet, it likely happens to anybody who manufactures anything in China. Simply put, China is the Far West when it comes to civil disputes; "we" ignore this state of things because the margins are still good enough to go there anyway. It's like running a supermarket in a bad part of town: as long as the profit it makes is higher than losses from vandalism and theft, it will stay open. At some point this might stop being the case.
Of course when Prometheus "stole" the fire from Mount Olympus he did not deny Zeus anything, but it was called theft. The fire that he brought to athens was the intellectual property of the Gods.
I don't know the actual situation, but let's say for the sake of argument;
- Apple pays $1M to make 1M chips, with the contract that forbids making these parts to sell third parties.
- A Shenzhen shop pays $15K to make 10K of the same parts, the manufacturer breaches the contract, violates Apple's IP and makes extra parts for the shop. None of this involves "theft" in any meaningful sense of the world.