SGPKit 4.1.0 and 4.2.0 released

Two new versions of SGPKit, 4.1.0 and 4.2.0, are now available.

4.1.0: Alpha-5 catalog numbers Link to heading

Satellite catalog numbers have five digits, so a TLE can’t hold a number above 99999. With the catalog crossing that limit, numbers from 100000 onward are written in the Alpha-5 format: a letter followed by four digits, such as A0000 for 100000.

Up to 4.0.0, SGPKit refused these TLEs. The bundled copy of libsgp4 predated its Alpha-5 support, so TLEInterpreter.satelliteData(from:date:) threw TLEInterpreter.Error.tle.

4.1.0 upgrades the bundled libsgp4 to v3.0, which reads Alpha-5 numbers. SARAMAGO, the first satellite numbered 100000, now propagates:

import SGPKit

let tle = try TLE(
    title: "SARAMAGO",
    firstLine: "1 A0000U 26067CY  26195.90649229  .00004770  00000+0  22159-3 0  9994",
    secondLine: "2 A0000  97.4593 154.0970 0005590 270.5113  89.5482 15.20467281 15911"
)

let data = try TLEInterpreter().satelliteData(from: tle, date: .now)

4.2.0: no more C++ interoperability for consumers Link to heading

Since 3.0.0, SGPKit has reached libsgp4 through a C++ wrapper. Swift’s C++ interoperability is contagious: every app or package that depended on SGPKit had to enable it too, either with .interoperabilityMode(.Cxx) in Package.swift or with Xcode’s C++ and Objective-C Interoperability build setting.

4.2.0 replaces the C++ wrapper with a plain C interface. libsgp4 is still C++ underneath, but SGPKit no longer exposes it, so consumers can remove the setting. The public Swift API is unchanged.

Thanks Link to heading

4.1.0 exists thanks to hneogy. Their issue #4 is what made me realize SGPKit couldn’t handle Alpha-5 catalog numbers. The report came with a reproducible example, the root cause, and the upstream version that fixed it, which made 4.1.0 a quick release. It also got me back to work on the library after almost a year, and 4.2.0 followed the same day.

Upgrading Link to heading

Update your Package.swift:

.package(url: "https://github.com/csanfilippo/swift-sgp4.git", from: "4.2.0")

Coming from 3.x Link to heading

4.0.0 changed how TLE decodes. It now decodes from the same keyed form it encodes, {"title": …, "firstLine": …, "secondLine": …}, so it survives a round trip through JSONEncoder and JSONDecoder. The array form [title, firstLine, secondLine] that 3.1.0 decoded no longer decodes. To migrate stored arrays, decode them as [String] and build the TLE yourself:

let lines = try JSONDecoder().decode([String].self, from: storedData)
let tle = try TLE(title: lines[0], firstLine: lines[1], secondLine: lines[2])

TLEEncoder and TLEDecoder, which read and write raw TLE text, are unchanged.

The full list of changes is in the changelog.