Localizable strings generator for Swift projects in Xcode

generate_strings.py

import os

def parse_input(input_path):
    with open(input_path, 'r') as f:
        lines = f.readlines()

    translations = {}
    for line in lines:
        line = line.strip()
        if not line.startswith('"') or '=' not in line:
            continue
        key, value = line.split('=', 1)
        key = key.strip('" ')
        value = value.strip(' ";')
        translations[key] = value

    return translations

def build_translation_tree(translations):
    tree = {}
    for key, value in translations.items():
        parts = key.split('.')
        node = tree
        for part in parts:
            if part not in node:
                node[part] = {}
            node = node[part]
        node['value'] = key

    return tree

def to_struct_name(name):
    parts = name.split('.')
    if len(parts) > 1:
        return parts[-2]
    return parts[0]

def generate_swift_code(t, translations, depth=1):
    code = ""
    indentation = '    ' * depth

    for key, subtree in t.items():
        if key == 'value':
            continue

        if 'value' in subtree:
            # Check if the translation value has a placeholder
            has_placeholder = "%@" in translations[subtree["value"]]

            if has_placeholder:
                code += f'{indentation}public static func {key}(_ value: String) -> String {{\n'
                code += f'{indentation}    return String(format: NSLocalizedString("{subtree["value"]}", comment: ""), value)\n'
                code += f'{indentation}}}\n'
            else:
                code += f'{indentation}public static var {key}: String {{\n'
                code += f'{indentation}    return NSLocalizedString("{subtree["value"]}", comment: "")\n'
                code += f'{indentation}}}\n'
        else:
            struct_name = to_struct_name(key)
            code += f'{indentation}public struct {struct_name} {{\n'
            code += generate_swift_code(subtree, translations, depth + 1)
            code += f'{indentation}}}\n'

    return code

def main():
    input_file_path = './Path/To/Localizable.strings/File'
    output_file_path = './Path/To/Strings.swift/File'

    translations = parse_input(input_file_path)
    translations_tree = build_translation_tree(translations)

    output = 'public struct Strings {\n'
    output += '    // MARK: - Common\n'
    for key, subtree in translations_tree.items():
        struct_name = to_struct_name(key)
        if 'value' in subtree:
            output += f'    public static var {key}: String {{\n'
            output += f'        NSLocalizedString("{subtree["value"]}", comment: "")\n'
            output += '    }\n'
        else:
            output += f'    public struct {struct_name} {{\n'
            output += generate_swift_code(subtree, translations, 2)
            output += '    }\n'
    output += '}\n'

    with open(output_file_path, 'w') as f:
        f.write(output)

if __name__ == "__main__":
    main()

Setup instructions:

1. Put this file in your project's root folder.
2. In main target's Build Phases section, create new Run Script phase.
3. Rename it to "Generate Strings" for better phases readability.
4. Move it to the very top as it allows you (usually, it would not go above "Run Build Tool Plug-ins" or "Target Dependencies").
5. Make sure Shell is "/bin/sh".
6. Add this script: "/usr/bin/python3 "${SRCROOT}/generate_strings.py" (without quotes).
7. Make sure "For install builds only" and "Based on dependency analysis" are deselected.
8. Build the project with some written strings keys and values in your Localizable.strings file.
9. The script should generate some output in your Strings.swift file.
10. Use the struct in your code.

This generation supports nested strings. It also supports single formatted string value (can be declared as "%@" in Localizable.strings file, e.g. "User.header" = "User %@";. So you can use it like this: Strings.User.header(userName)