Swift User Guide

This section explains how to work with the Swift file generator.

Scrooge supports generation of the Swift model classes. The thrift files need to have this namespace definition: #@namespace swift ThriftEncoding. Scrooge creates the models as a Swift package with that namespace as the name.

The generated swift uses TwitterApacheThrift<https://github.com/twitter/ios-twitter-apache-thrift>.

Objective-C Compatibility

The default is to create Swift only types. Scrooge has the ability to generate the models with Objective-C compatibility. This command line argument is --language-flag 'swift-objc prefix', with the prefix being the Obj-C class prefix. Note: The apostrophes are required. Enums will add @objc and structs will become NSObject classes. Unions will be Enums with raw type wrapped in an NSObject class with initializers for each case. The swift encoder and decoder classes will remain Swift only. This allows this library to be a drop-in replacement for current ApacheThrift library.

Swift Classes

Scrooge can also generate non-NSObject classes instead of structs. To enable this pass --language-flag swift-classes to scrooge generation command.

Note

When passing both the objective-c compatibility and swift class arguments. The swift class argument does nothing.

Access Control

Scrooge can also generate for internal interfaces instead of public interfaces. To enable this pass --language-flag internal-types to scrooge generation command.

Type naming

Swift doesn’t support namespaces the same way as JVM languages. Scrooge uses an annotation on the thrift models to generate different type names. These new annotations will be available for Structs, Unions, and Enums. The following thrift will create a swift Struct with the name of UserV1.

struct User {
  1: required i64 id
}(alternative.type = 'UserV1')

// Generated from thrift
public struct UserV1: ThriftCodable {
  let id: Int64
  ...
}

Generation Command

Here is some example command to generate the swift models from thrift.

# Generates swift structs
$ ./sbt 'scrooge-generator/runMain com.twitter.scrooge.Main -l swift -d generated -s your_file.thrift'

# Generates swift with obj-c compatibility
$ ./sbt "scrooge-generator/runMain com.twitter.scrooge.Main -d generated -l swift --language-flag 'swift-objc prefix' -s your_file.thrift"

# Generates swift with classes instead of structs
$ ./sbt 'scrooge-generator/runMain com.twitter.scrooge.Main -d generated -l swift --language-flag swift-classes -s your_file.thrift'