The String Catalog (.xcstrings) format is Apple's modern localization system, designed to streamline internationalization for iOS, macOS, watchOS, and tvOS applications. It uses a JSON-based structure that is both human-readable and optimized for development tools.

String Catalogs are intended to replace the older Apple iOS .strings and .stringsdict formats.

Format

The format is based on JSON.
The file extension is .xcstrings.
Placeholder information follows the Apple String Format Specifiers reference.
String Catalogs are multi-language files containing translation information for multiple locales within a single file.
The format uses variations to manage different translation contexts:
- Plurals: Handles pluralization rules.
- Devices: Handles device-specific strings (e.g., iPhone, iPad, Mac). LingoHub currently stores the default device variation.
- Substitutions: Enables type-safe placeholders for dynamic variable insertion.
LingoHub maps the Xcode string catalog state to segment states as follows:
- new → NEW.
- stale → DRAFT.
- needs_review → TRANSLATED.
- translated → APPROVED.

LingoHints can be included in a comment attribute:

"accessibility_settings": {
  "comment": "Show accessibility settings. <lh>{\"status\": \"DRAFT\",\"qc\": {\"min\": \"3\",\"max\": \"20\"},\"labels\": [\"q3-2024\"],\"not_translatable\": false}</lh>",
  "localizations": {
    "de": {
      "stringUnit": {
        "state": "translated",
        "value": "Barrierefreiheit"
      }
    }
  }
}

Example

{
  "sourceLanguage": "en",
  "strings": {
    "photos_count": {
      "extractionState": "manual",
      "localizations": {
        "de": {
          "state": "translated",
          "variations": {
            "plural": {
              "zero": "Keine Fotos",
              "one": "Ein Foto",
              "other": "%lld Fotos"
            }
          }
        },
        "en": {
          "state": "verified",
          "variations": {
            "plural": {
              "zero": "No photos",
              "one": "One photo",
              "other": "%lld photos"
            }
          }
        }
      }
    },
    "welcome_message": {
      "extractionState": "manual",
      "localizations": {
        "de": {
          "state": "translated",
          "variations": {
            "device": {
              "ipad": "Willkommen auf deinem iPad",
              "iphone": "Willkommen auf deinem iPhone",
              "mac": "Willkommen auf deinem Mac",
              "other": "Willkommen"
            }
          }
        }
      }
    }
  },
  "version": "1.0"
}

Xcode String Catalogs

Format

Example

References