SwiftyJSCore wraps JavaScriptCore Framework and provides a convenient way to call JavaScript functions from Swift.
SwiftyJSCore supports:
- asynchronous functions/promises mapped from JS to Swift
- encoding and decoding
Codabletypes in both directions - exception handling
- basics of Fetch API supporting json() response
Note
If your application targets iOS and performance is important to you, consider using WKWebView. WKWebView, running in a separate process not having security issues, uses JIT compiler making JS considerably faster compared to JavaScriptCore.
JavaScript:
var testString = () => {
return "Foobar";
}
var testAsync = async (arg) => {
return { "id": arg.id, "name": "Test" }
}
var testException = async () => {
throw new TypeError("TestError");
}Swift:
let interpreter = try await JSInterpreter()
try await interpreter.evaluateFile(url: jsURL)
try await interpreter.eval("console.log(\"8+13=\", 8+13)")
try await interpreter.setObject(13, forKey: "thirteen")
let sum: Int = try await interpreter.eval("thirteen+8")
assert(sum == 21)
let string: String = try await interpreter.call(function: "testString")
assert(string == "Foobar")You can pass Codable entities and typical JavaScriptCore @objc/NSObject classes as function arguments.
Return values map to Swift primitives or Codable.
struct TestEntity: Codable {
let id: Int
let name: String
}
let entity: TestEntity = try await interpreter.call(
function: "testAsync",
arguments: [TestEntity(id: 123, name: "Foobar")])
assert(entity.id == 123 && entity.name == "Test")
do {
let _: Int = try await interpreter.call(function: "testException")
} catch JSError.exception(let name, let message) {
assert(name, "TypeError")
assert(message, "TestError")
}