[Swift] Overall Improvements

[mustiikhalil]

The following PR adds the following:

• Removes a warning that has shown up within Xcode 15, and swift 5.9. Closes [Swift, master] Address XC15/Swift 5.9 UnsafeRawPointer Warning #8064

Benchmarks are impressive compared to what we used to have:

Updated code:

running 10Strings... done! (1522.66 ms)
running 100Strings... done! (1781.41 ms)
running FlatBufferBuilder.add... done! (1542.41 ms)
running structs... done! (1478.57 ms)

Old code:

running 10Strings... done! (1422.76 ms)
running 100Strings... done! (1705.70 ms)
running FlatBufferBuilder.add... done! (2309.38 ms)
running structs... done! (2305.26 ms)

• Upgrades minimum version of swift to 5.5
• Allow reading unaligned buffers starting from swift 5.7, while keeping the creating aligned since it's created by the library.

Unfortunately, swift package manager doesn't allow custom compiler flags so I had to use a normal if statement to resolve this. the flag is false by default so it shouldn't be an issue most of the time, however when needed users can enable it like this:

var buffer = ByteBuffer(data: dataFromInternet)
buffer.readUnalignedBuffers = true
...

@mr-swifter @ser-0xff @hassila a quick review here would be nice!

[hassila]

Out traveling - will try to have a look next week!

[hassila]

Otherwise, LGTM - on a separate note, I think it would be nice to consider moving to (https://github.com/ordo-one/package-benchmark) later on when we get 5.7 as the baseline supported and look at extending the set of benchmarks a bit, but will open a separate issue for that later when the baseline has moved...

[mustiikhalil]

@hassila correct me if I am wrong here but should it just work? Since we can configure the benchmark package to run on only 5.7?

[hassila]

Yeah, maybe you are right - but in general it's nice to have numbers that are comparable across toolchain versions too?

[mustiikhalil]

Oh yeah for sure, but since benchmark package is only supporting 5.7+, we can sacrifice benchmarks on 5.5, and 5.6. So we can focus on future toolchains.

I've added it to the roadmap #6467 (comment)

[hassila]

Wrt package-benchmark I'd suggest adopting similar structure as is done here: apple/swift-certificates#125

Then no top level project dependency is needed and it's fine with 5.7+ now.

[mustiikhalil]

Definitely we can use that! I guess we can start working on it on a different PR