I'm wrong about that - it was the Exynos 3110 that had the Apple designed core that also appeared in the A4. And after that, it was back to ARM's humble designs for Samsung.
Hummingbird in SGS2 (this was before rename to Exynos) and A4 in iPhone 4 stem from cooperation between Samsung and Apple (who previously used Samsung SoC in iPhone 3G and I think in 2G). The teams split before both phones reached maturity in design. From then on Samsung kept iterating on the Hummingbird design till I think quite recently - I'm not sure if my Note 10+ doesn't still have cores derived from that design.
