---

title: Swift sidebar_position: 9 id: swift license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Output Layout

Swift output is one .swift file per schema, for example:

• <swift_out>/addressbook/addressbook.swift

Type Generation

The generator creates Swift models with split model macros and stable field/case IDs. A typed union must include @ForyUnknownCase case unknown(UnknownCase) and at least one non-unknown case; unknown(UnknownCase) is only the Fory-provided forward-compatibility carrier. The marker only selects the carrier and does not add an entry to the schema case table.

When package/namespace is non-empty, namespace shaping is controlled by swift_namespace_style:

• enum (default): nested enum namespace wrappers.
• flatten: package-derived prefix on top-level type names (for example Demo_Foo_User).

When package/namespace is empty, no enum wrapper or flatten prefix is applied.

For non-empty package with default enum style:

public enum Addressbook {
    @ForyUnion
    public enum Animal {
        @ForyUnknownCase
        case unknown(UnknownCase)
        @ForyCase(id: 0)
        case dog(Addressbook.Dog)
        @ForyCase(id: 1)
        case cat(Addressbook.Cat)
    }

    @ForyStruct
    public struct Person: Equatable {
        @ForyField(id: 1)
        public var name: String = ""
        @ForyField(id: 8)
        public var pet: Addressbook.Animal =
            Addressbook.Animal.dog(Addressbook.Dog())
    }
}

For non-empty package with flatten style:

@ForyStruct
public struct Addressbook_Person: Equatable { ... }

The CLI flag --swift_namespace_style overrides schema option swift_namespace_style when both are set.

Unions are generated as tagged Swift enums with associated payload values. Recursive unions are emitted as indirect enums. The first known union case must have a finite recursively constructible default; the compiler rejects a first-case default cycle instead of emitting a non-terminating initializer. Messages with ref/weak_ref fields are generated as final class models to preserve reference semantics. A directly stored message cycle must mark at least one cycle edge ref; otherwise the compiler rejects the schema because Swift value types cannot represent it. Fixed or tagged integer encodings inside list/map fields are emitted as Swift field type hints, for example @ListField(element: .encoding(.fixed)) or @MapField(value: .encoding(.tagged)). For non-null fixed-width integer list elements, Swift classifies the field as the corresponding Fory primitive packed-array type; fixed-width integer sets remain Fory sets.

Module Installation

Each schema includes a ForyModule owner with transitive import installation:

public enum ForyModule {
    public static func install(_ fory: Fory) throws {
        try ComplexPb.ForyModule.install(fory)
        try fory.register(Addressbook.Person.self, id: 100)
        try fory.register(Addressbook.Animal.self, id: 106)
    }
}

With non-empty package and flatten style, the helper is prefixed too (for example Addressbook_ForyModule).

For schemas without explicit [id=...], installation uses computed numeric IDs. If option enable_auto_type_id = false; is set, generated code uses name-based registration APIs.