You mean the same vertical integration Microsoft is doing buying 3P publishers to fold their operations and revenue into Xbox/Microsoft Gaming? The same vertical integration Microsoft utilizes in the PC space between Windows, OS bundling deals with OEMs, Direct X SDK, Visual Basic, and a closed-off proprietary kernel? A pipeline where they have complete presence in every single step (hardware, software, SDKs, middleware, storefront, manufacturers, standardization)?
Apple designs iOS for their devices. That is not anticompetitive; you don't even seem to know what that word means, just throwing it around because it sounds impactful.
Also from what I understand, vertical integrations are not inherently anticompetitive; they potentially CAN be, but trying to hard associate the concept with anticompetitive practices itself is dishonest. There are lots of reason why Apple can argue their implementation is not anticompetitive, they can even technically point to companies like Nintendo as an example in some instances.
There is nothing inherently anticompetitive about a closed ecosystem.