A Zcash Lightweight Client SDK for iOS This is an alpha build and is currently under active development. Please be advised of the following:
- This code currently is not audited by an external security auditor, use it at your own risk
- The code has not been subjected to thorough review by engineers at the Electric Coin Company
- We are actively changing the codebase and adding features where/when needed
🔒 Security Warnings
- The Zcash iOS Wallet SDK is experimental and a work in progress. Use it at your own risk.
- Developers using this SDK must familiarize themselves with the current threat model, especially the known weaknesses described there.
Add a package with the source "https://github.com/zcash/ZcashLightClientKit.git" and from version 0.14.0-beta onwards in either Xcode's GUI or in your Package.swift file.
If you want to include a beta version of ZCashLightClientKit in an Xcode project e.g 0.14.0-beta you will need to specify it with the commit sha instead as it does not appear that Xcode supports 'meta data' from semantic version strings for swift packages (at the time of writing).
The best way to run tests is to open "Package.swift" in Xcode and use the Test panel and target an iOS device. Tests will build and run for a Mac target but are not currently working as expected.
There are three test targets grouped by external requirements:
OfflineTests- No external requirements.
NetworkTests- Require an active internet connection.
DarksideTests- Require an instance of
lightwalletdto be running while the tests are being run, see below for some information on how to set up. (Darkside refers to a mode in lightwalletd that allows it to be updated to represent/mock different states of the underlying blockchain.)
- Require an instance of
The DarksideTests test target depend on a lightwalletd server instance running locally (or remotely). For convenience, we have added a universal (Mac) lightwalletd binary (in `Tests/lightwalletd/lightwalletd) and it can be run locally for use by the tests with the following command:
Tests/lightwalletd/lightwalletd --no-tls-very-insecure --data-dir /tmp --darkside-very-insecure --log-file /dev/stdout
You can find out more about running lightwalletd, from the main repo https://github.com/zcash/lightwalletd.
The LIGHTWALLETD_ADDRESS environment variable can also be added to your shell of choice and xcodebuild will pick it up accordingly.
We advise setting this value as a secret variable on your CD/CI environment when possible.
There are a lots of good logging tools for iOS. So we'll leave that choice to you. ZcashLightClientKit relies on a simple protocol to bubble up logs to client applications, which is called Logger (kudos for the naming originality...)
public protocol Logger {
func debug(_ message: String, file: String, function: String, line: Int)
func info(_ message: String, file: String, function: String, line: Int)
func event(_ message: String, file: String, function: String, line: Int)
func warn(_ message: String, file: String, function: String, line: Int)
func error(_ message: String, file: String, function: String, line: Int)
}
You have a few different options when it comes to logging:
-
Leave it to the SDK. It will use its own
Loggerwith sensible defaults. For this option, simply omit theloggingPolicyparameter when creating theInitializer -
Provide a custom logger. For this option, do the following: a). have one class conform to the
Loggerprotocol b). inject that logger when creating theInitializerby passing aloggingPolicyof.custom(yourLogger) -
No logging. The SDK will not log any events. For this option, pass a
loggingPolicyof.noLoggingwhen creating theInitializer
For more details look the Sample App's AppDelegate code.
We don't like reinventing the wheel, so we gently borrowed swift lint rules from AirBnB which we find pretty cool and reasonable.
The CompactBlockProcessor is responsible for downloading and processing blocks from the lightwalletd. Since the inception of the SDK the blocks were processed in a linear order up to the chain tip. Latests SDK has introduced brand new algorithm for syncing of the blocks. It's called Spend before Sync and processes blocks in non-linear order so the spendable funds are discovered as soon as possible - allowing users to create a transaction while still syncing.
This project follows semantic versioning with pre-release versions. An example of a valid version number is 1.0.4-alpha11 denoting the 11th iteration of the alpha pre-release of version 1.0.4. Stable releases, such as 1.0.4 will not contain any pre-release identifiers. Pre-releases include the following, in order of stability: alpha, beta, rc. Version codes offer a numeric representation of the build name that always increases. The first six significant digits represent the major, minor and patch number (two digits each) and the last 3 significant digits represent the pre-release identifier. The first digit of the identifier signals the build type. Lastly, each new build has a higher version code than all previous builds. The following table breaks this down:
| Type | Purpose | Stability | Audience | Identifier | Example Version |
|---|---|---|---|---|---|
| alpha | Sandbox. For developers to verify behavior and try features. Things seen here might never go to production. Most bugs here can be ignored. | Unstable: Expect bugs | Internal developers | 0XX | 1.2.3-alpha04 (10203004) |
| beta | Hand-off. For developers to present finished features. Bugs found here should be reported and immediately addressed, if they relate to recent changes. | Unstable: Report bugs | Internal stakeholders | 2XX | 1.2.3-beta04 (10203204) |
| release candidate | Hardening. Final testing for an app release that we believe is ready to go live. The focus here is regression testing to ensure that new changes have not introduced instability in areas that were previously working. | Stable: Hunt for bugs | External testers | 4XX | 1.2.3-rc04 (10203404) |
| production | Delivery. Deliver new features to end users. Any bugs found here need to be prioritized. Some will require immediate attention but most can be worked into a future release. | Stable: Prioritize bugs | Public | 8XX | 1.2.3 (10203800) |
This repo contains demos of isolated functionality that this SDK provides. They can be found in the examples folder.
Examples can be found in the Demo App.
MIT