Custom Structs (interface)

Any custom interface or type that does not extend HybridObject will be represented as a fully type-safe struct in C++/Swift/Kotlin. Simply define the type in your .nitro.ts spec:

Nitro.nitro.ts

interface Person {
  name: string
  age: number
}

interface Nitro extends HybridObject {
  getAuthor(): Person
}

HybridNitro.swift

class HybridNitro: HybridNitroSpec {
  func getAuthor() -> Person {
    return Person(name: "Marc", age: 24)
  }
}

Nitro enforces full type-safety to avoid passing or returning wrong types. Both name and age are always part of Person, they are never a different type than a string/number, and never null or undefined.

This makes the TypeScript definition the single source of truth, allowing you to rely on types! 🤩

Structs are eagerly converted

Since structs are just flat value types, each key/value is eagerly converted from a JS value to a native value (and vice-versa) when passing them between JS and native.

This is fine for small structs and benefits from low allocation cost, but contains an overhead when your structs growing larger. Use Hybrid Objects to implement a way to lazily convert each key/value instead.