Fix visionOS availability error for split(by:) method

[danielseidl]

Summary

• Fixes compiler error where split(by:) was unavailable on visionOS
• Extracts split logic into a helper method using compile-time platform conditional

Environment

• Xcode 26.4 beta (17E5159k)

Problem

The existing code used a runtime #available check to choose between split(separator:) (new API) and split(by:) (legacy fallback):

let rawMessages: [Data] = if #available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, visionOS 1.0, *) {
    data[bufferRange].split(separator: separator)
} else {
    data[bufferRange].split(by: separator)
}

While visionOS 1.0+ would always take the if branch at runtime, Swift still type-checks the else branch at compile time, causing an error because split(by:) is marked unavailable for visionOS.

Solution

Replaced the inline conditional with a new splitData(_:separator:) helper that uses #if os(visionOS) compile-time conditional to completely exclude the legacy code path on visionOS builds:

private func splitData(_ data: Data, separator: [UInt8]) -> [Data] {
    #if os(visionOS)
    return data.split(separator: separator)
    #else
    if #available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *) {
        return data.split(separator: separator)
    } else {
        return data.split(by: separator)
    }
    #endif
}

Test Plan

• Project builds successfully
• Verify builds on visionOS target
• Run existing EventParserTests to ensure parsing behavior unchanged

[Recouse]

That's a good catch, thank you!