Restrict Apple plural forms to named categories and fold =0 into zero

munzzyy · munzzyy · commit 6f7f077cd441 · 2026-08-10T12:02:10.000-05:00
populateForms merged every authored form key wholesale, so an ICU =N exact
match (e.g. =0) went into the XLIFF as a =N quantity key, which the Apple
plural formats don't accept. Keep the locale's CLDR forms plus any authored
named category (zero/one/two/few/many/other) and drop the =N keys. When a
plural has an =0 but no explicit zero, surface it as zero, which is the
closest thing stringsdict/xcstrings can express.
diff --git a/backend/data/src/main/kotlin/io/tolgee/formats/apple/out/AppleXliffExporter.kt b/backend/data/src/main/kotlin/io/tolgee/formats/apple/out/AppleXliffExporter.kt
@@ -5,6 +5,7 @@ import io.tolgee.formats.PossiblePluralConversionResult
 import io.tolgee.formats.apple.APPLE_CORRESPONDING_STRINGS_FILE_ORIGINAL
 import io.tolgee.formats.apple.APPLE_FILE_ORIGINAL_CUSTOM_KEY
 import io.tolgee.formats.apple.APPLE_PLURAL_PROPERTY_CUSTOM_KEY
+import io.tolgee.formats.formKeywords
 import io.tolgee.formats.getPluralFormsForLocale
 import io.tolgee.formats.xliff.model.XliffFile
 import io.tolgee.formats.xliff.model.XliffModel
@@ -233,12 +234,19 @@ class AppleXliffExporter(
     conversionResult: PossiblePluralConversionResult?,
   ): Map<String, String> {
     val forms = conversionResult?.formsResult ?: return emptyMap()
-    // Apple's plural formats (stringsdict/xcstrings) accept any form the user actually wrote
-    // (e.g. "zero"), not just the forms CLDR defines for the target locale, so we keep every
-    // authored form in addition to filling in the ones CLDR expects (e.g. "many" for cs).
     val otherForm = forms["other"] ?: ""
-    val allForms = getPluralFormsForLocale(languageTag) + forms.keys
-    return allForms.associateWith { forms[it] ?: otherForm }
+    // Apple's plural formats (stringsdict/xcstrings) take the CLDR forms for the locale plus any
+    // named category the user actually wrote (e.g. "zero" for en), but only the six named
+    // categories — Apple has no equivalent for ICU "=N" exact matches, so those are dropped.
+    val authoredNamedForms = forms.keys.filter { it in formKeywords }
+    val allForms = getPluralFormsForLocale(languageTag) + authoredNamedForms
+    val result = allForms.associateWithTo(mutableMapOf()) { forms[it] ?: otherForm }
+    // Apple can't express an "=0" exact match, so if the user wrote one and there is no explicit
+    // "zero", surface it as "zero" — the closest the format has.
+    if ("zero" !in result) {
+      forms["=0"]?.let { result["zero"] = it }
+    }
+    return result
   }
 
   private fun getResultXliffFile(
diff --git a/backend/data/src/test/kotlin/io/tolgee/unit/formats/apple/out/AppleXliffFileExporterTest.kt b/backend/data/src/test/kotlin/io/tolgee/unit/formats/apple/out/AppleXliffFileExporterTest.kt
@@ -353,6 +353,51 @@ class AppleXliffFileExporterTest {
     )
   }
 
+  @Test
+  fun `folds an explicit =0 into the zero form Apple can express`() {
+    val built =
+      buildExportTranslationList {
+        add(
+          languageTag = "en",
+          keyName = "attendee_count",
+          text = "{count, plural, =0 {No participants} one {1 Participant} other {Many participants}}",
+        ) {
+          key.isPlural = true
+          key.custom = mapOf(APPLE_FILE_ORIGINAL_CUSTOM_KEY to "Localizable.xcstrings")
+        }
+      }
+    val exporter = getExporter(built.translations, emptyList())
+    val data = getExported(exporter)
+    data.assertFile(
+      "en.xliff",
+      """
+    |<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+    |<xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" version="1.2">
+    |  <file datatype="plaintext" original="Localizable.xcstrings" source-language="tag" target-language="en">
+    |    <header>
+    |      <tool tool-id="tolgee.io" tool-name="Tolgee"/>
+    |    </header>
+    |    <body>
+    |      <trans-unit id="attendee_count|==|plural.one">
+    |        <source xml:space="preserve"/>
+    |        <target xml:space="preserve">1 Participant</target>
+    |      </trans-unit>
+    |      <trans-unit id="attendee_count|==|plural.other">
+    |        <source xml:space="preserve"/>
+    |        <target xml:space="preserve">Many participants</target>
+    |      </trans-unit>
+    |      <trans-unit id="attendee_count|==|plural.zero">
+    |        <source xml:space="preserve"/>
+    |        <target xml:space="preserve">No participants</target>
+    |      </trans-unit>
+    |    </body>
+    |  </file>
+    |</xliff>
+    |
+      """.trimMargin(),
+    )
+  }
+
   @Test
   fun `honors the provided fileStructureTemplate`() {
     val exporter =
