Update Swift package for release

Replace `Package.swift` to build the package from `./Sources` (generated Swift bridge code)
and the binaries built from the previous commit and pushed as a "release" in the repo.

This completes the migration of the repo from its former use
as a simple package spec for the legacy `mobile_wallet` library
to the new one which is embedded in the repo.

Future releases are to follow the same two-step process layed out by this commit and its predecessor;
i.e. two conscutive, tagged commits within a single PR.
The complete process is described in the README.

Package.swift

@@ -1,16 +1,30 @@
-// swift-tools-version: 5.6
+// swift-tools-version:5.6
 
 import PackageDescription
 
 let package = Package(
     name: "ConcordiumWalletCrypto",
+    platforms: [
+        .iOS(.v13),
+        .macOS(.v10_15),
+    ],
     products: [
         .library(
             name: "ConcordiumWalletCrypto",
-            targets: ["libmobile_wallet"]),
+            targets: ["ConcordiumWalletCrypto"]
+        ),
     ],
-    dependencies: [],
     targets: [
-        .binaryTarget(name: "libmobile_wallet", url: "https://s3.eu-west-1.amazonaws.com/static-libraries.concordium.com/iOS/libmobile_wallet_0.24.0-0.xcframework.zip", checksum: "8051b9681901187537adc76858715d569d51abd4c201c376f292749da0b6eb60")
+        .binaryTarget(
+            name: "RustFramework",
+            url: "https://github.com/Concordium/concordium-wallet-crypto-swift/releases/download/build%2F1.0.0-1/RustFramework.xcframework.zip",
+            checksum: "edc2628d1721697b555891316dac3be1490072c1649d040fff8f3c160b2d0e09"
+        ),
+        .target(
+            name: "ConcordiumWalletCrypto",
+            dependencies: [
+                .target(name: "RustFramework"),
+            ]
+        ),
     ]
 )

README.md

@@ -1,30 +1,60 @@
 # ConcordiumWalletCrypto
 
-[Swift package](https://developer.apple.com/documentation/xcode/swift-packages) providing Concordium's [Rust-based crypto library for mobile wallets](https://github.com/Concordium/concordium-base/tree/main/mobile_wallet), compiled for iOS as an [XCFramework](https://developer.apple.com/documentation/xcode/distributing-binary-frameworks-as-swift-packages).
+[Swift package](https://developer.apple.com/documentation/xcode/swift-packages) providing bindings for Swift
+of Concordium specific cryptographic functions that are written in Rust.
 
-The binaries are compiled internally and uploaded to S3. The only target of the package is a binary target that references the appropriate version of this file.
+The project is a core component of [`ConcordiumSwiftSdk`](https://github.com/Concordium/concordium-swift-sdk.git)
+and only has its own repository because of limitations in SwiftPM
+that prevent us from publishing everything in a single complete package.
+In brief, Swift packages must be downloaded straight from git,
+not from a registry to which we can publish the complete build.
+This repository serves the dual purpose of hosting the Rust sources while simultaneously standing in as such a registry.
 
-## Versioning
+To avoid storing large binaries in git, a workflow compiles the bindings into an
+[XCFramework](https://developer.apple.com/documentation/xcode/distributing-binary-frameworks-as-swift-packages)
+and uploads it to GitHub as a release in this repository.
 
-The available versions of the package are represented by the commit tags of this repository.
+The package specification then refers to such a release, not the local Rust sources.
+This means that the Swift sources (i.e. generated bridge code) and package spec made up by this repo
+and its Rust sources aren't necessarily in sync.
+The Swift files always refer to the latest published release, even during development of the next version.
 
-The version follows the one of the [Rust sources](https://github.com/Concordium/concordium-base/blob/main/mobile_wallet/Cargo.toml) with a "build version" appended with a `-` separator. This extra component counts from 0 for any given library version and is bumped whenever a new Swift package based on the same Rust sources is built.
+## Previous usage
 
-## Relase new version
+This repository/package was previously used to host the binaries built from a previous incarnation of the Rust library
+which was built and hosted elsewhere.
+See commit 6b6af29816b0f966598b170d62334e2faf00062b for details.
 
-Steps for building and releasing a new version `<version>`:
+That package is still available from tag
+[`0.24.0-0`](https://github.com/Concordium/concordium-wallet-crypto-swift/releases/tag/0.24.0-0)
+and in use by the
+[iOS reference wallet](https://github.com/Concordium/concordium-reference-wallet-ios/).
 
-1. Using the appropriate automated job, run [`./build-ios.sh`](https://github.com/Concordium/concordium-base/blob/main/mobile_wallet/scripts/build-ios.sh) from `concordium-base`, archive `ios/build/libmobile_wallet.xcframework` as a compressed zip file named `libmobile_wallet_<version>.xcframework.zip`, and upload this file to S3 bucket/path `static-libraries.concordium.com/iOS/`.
+## Versioning
 
-2. Compute checksum of the archive using the command
-   ```shell
-   swift package compute-checksum libmobile_wallet_<version>.xcframework.zip
-   ```
+The available versions of the package are represented by the commit tags of this repository.
+The version is defined by the Rust/Cargo project.
+
+## Release new version
 
-3. Commit a change to [`Package.swift`](https://github.com/Concordium/concordium-wallet-crypto-swift/blob/main/Package.swift), updating the `libmobile_wallet` binary target with the new version in the `url` string and the new `checksum`.
+The Rust code is developed as usually without making changes to `./Sources` nor `Package.swift`.
 
-4. Push an annotated tag named by the version for the new commit:
+Once it's ready for a new release, the steps for building and releasing a new version `<version>` are:
+
+1. Create and push a tag named `build/<version>-<build-version>`,
+   where `<build-version>` is bumped (starting from 0) for each attempt at building `<version>`.
+   This is necessary because GitHub requires releases to be tagged and the following workflow uploads a release.
+2. Run the [workflow](./.github/workflows/publish-bindings.yml) for publishing a new version of the binary framework.
+   Use the tag you just created as "branch" to run from and input `<version>` (i.e. without the counter for "Version").
+3. Run [`./build.sh`](./build.sh) locally to regenerate the Swift bridge sources.
+   [TODO: Running the "bindgen" step is sufficient.]
+4. Update `Package.swift` with the updated `url` and `checksum` of the binary framework.
+   The workflow prints the checksum as the last step of its execution.
+5. Commit the changes and push an annotated tag named by the version for the new commit:
    ```shell
    git tag -a <version>
    ```
    Give the tag a message describing what changed in the new version.
+
+The entire process should be done as a single PR which,
+in order to preserve the tags, gets merged without squashing.