ProtobufKit

ProtobufKit is a lightweight¹ replacement of swift-protobuf for working with Protocol Buffers serialization technology in Swift.

Overview

ProtobufKit is a cross-platform Swift package on Darwin platform (without OS version limitation) and Linux.²

Workflow	CI Status
Compatibility Test
macOS Unit Test
iOS Unit Test
Ubuntu 22.04 Unit Test

ProtobufKit is compatible³ with the latest SwiftUI's internal Protobuf implementation so that you can use it to decode some internal binary data of SwiftUI (eg. ArchivedView).

The core design of ProtobufKit is ProtobufMessage which is similar to Codable and easy to customize.

public protocol ProtobufEncodableMessage {
    func encode(to encoder: inout ProtobufEncoder) throws
}
public protocol ProtobufDecodableMessage {
    init(from decoder: inout ProtobufDecoder) throws
}

public typealias ProtobufMessage = ProtobufDecodableMessage & ProtobufEncodableMessage

You can also use it with Codable by conforming your message type to CodaleByProtobuf or annoate your message instance with ProtobufCodable propertyWrapper.

Getting Started

In your Package.swift file, add the following dependency to your dependencies argument:

.package(url: "https://github.com/OpenSwiftUIProject/ProtobufKit.git", from: "0.1.0"),

Then add the dependency to any targets you've declared in your manifest:

.target(
    name: "MyTarget", 
    dependencies: [
        .product(name: "ProtobufKit", package: "ProtobufKit"),
    ]
),

To make a type conform to ProtobufMessage, you need to implement the init(from:) and encode(to:) methods the same as Codable usage.

But instead of using CodingKeys, we use ProtobufTag or UInt here to define the field number.

import ProtobufKit

struct SimpleMessage: ProtobufMessage {
    let value: Bool
    init(from decoder: inout ProtobufDecoder) throws {
        while let field = try decoder.nextField() {
            switch field.tag {
            case 1:
                value = try decoder.boolField(field)
                return
            default: try decoder.skipField(field)
            }
        }
        value = false
    }
    func encode(to encoder: inout ProtobufEncoder) throws {
        encoder.boolField(1, value)
    }
}

Please see ProtobufKit documentation site for more detailed information about the library.

Future work

ProtobufKit does not have compiler build-in support like Codable, so you have to write the encode and decode logic by yourself.

This can be improved by future macro API like the following.

struct SimpleMessage: ProtobufMessage {
    @Field(tag: 1, type: .bool)
    var value: Bool
}

License

See LICENSE file - MIT

Related Projects

• https://github.com/OpenSwiftUIProject/OpenSwiftUI

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Footnotes

1. Under macOS + Build for profiling option, ProtobufKit's ProtobufKit.o is 142KB while swift-protobuf's SwiftProtobuf.o is 5.7MB ↩

2. WASI support will be added in the future ↩

3. Compatibility with SwiftUI may break in the future SwiftUI release ↩