Add dependencies on GCDWebServer and PINCache

[twogood]

Trying to fix part of #714

To be more exact, try to fix this error message, which sometimes also lists GCDWebServer:

    Undefined symbols for architecture arm64:
      "_OBJC_CLASS_$_PINCache", referenced from:
          objc-class-ref in CacheManager.o
    ld: symbol(s) not found for architecture arm64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)

[jhomlala]

@twogood Before merging this PR I need to know when does this problem occur. Can you prepare some reproducible example?

[twogood]

You know the old saying:

| The definition of insanity is doing the same thing over and over again and expecting a different result.

The client project that me and my team have inherited and are currently working on failed on compile most of the time before adding these as explicit dependencies. We have spent many hours trying to figure out why. With this patch it works every time.

Linkers are a species of their own. There is even a "classic" book called "Linkers and loaders" for those who want to know more how linkers work.

But I digress. I don't have an isolated example but as the better player code explicitly references these pods they should also be explicit references from the better player pod. It is unwise to depend on transitive dependencies.

[twogood]

This article shows a cocoa pods example for specifying the same dependency on different levels in the dependency tree with proper version resolving:

https://link.medium.com/9xXAjB5cZkb

[twogood]

Here is an example that (sometimes) fails the same way:

https://github.com/twogood/better_player_pr787

Can happen with "Play" button in XCode, also with flutter build ios or flutter build ipa

[twogood]

[twogood]

And sometimes... "Build succeeded"

[ndahlquist]

For what it's worth, I also experienced this error yesterday (and then it resolved itself after a clean build). Seems like a good idea to explicitly add the transitive dependencies if it can make the build more reliable!

[twogood]

Actually they are also direct dependencies in the source code:

[aignerjo]

+1

@twogood's solution works.

[ndahlquist]

I added this patch too! No more linker errors :)

[garlicPasta]

It also fixed the error for me when building for a real device 👍
Simulator was not having this error.

[windows7lake]

It’s help

[jhomlala]

LGTM, thanks.