diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
index e5f4b90614a5..7d2a1d9d5154 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
@@ -769,7 +769,8 @@ public String apiFileFolder() {
     public String getTypeDeclaration(Schema p) {
         if (ModelUtils.isArraySchema(p)) {
             Schema inner = ModelUtils.getSchemaItems(p);
-            return ModelUtils.isSet(p) ? "Set<" + getTypeDeclaration(inner) + ">" : "[" + getTypeDeclaration(inner) + "]";
+            String innerTypeDeclaration = getItemsTypeDeclaration(inner);
+            return ModelUtils.isSet(p) ? "Set<" + innerTypeDeclaration + ">" : "[" + innerTypeDeclaration + "]";
         } else if (ModelUtils.isMapSchema(p)) {
             Schema inner = ModelUtils.getAdditionalProperties(p);
             return "[String: " + getTypeDeclaration(inner) + "]";
@@ -777,6 +778,13 @@ public String getTypeDeclaration(Schema p) {
         return super.getTypeDeclaration(p);
     }
 
+    private String getItemsTypeDeclaration(Schema items) {
+        String itemsTypeDeclaration = getTypeDeclaration(items);
+        Schema itemsSchema = ModelUtils.getReferencedSchema(openAPI, unaliasSchema(items));
+        String nullable = ModelUtils.isNullable(itemsSchema) && !itemsTypeDeclaration.endsWith("?") ? "?" : "";
+        return itemsTypeDeclaration + nullable;
+    }
+
     @Override
     public String getSchemaType(Schema p) {
         String openAPIType = super.getSchemaType(p);
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift6ClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift6ClientCodegen.java
index 3af8f6805235..7cd975547f2c 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift6ClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift6ClientCodegen.java
@@ -815,7 +815,8 @@ public String apiFileFolder() {
     public String getTypeDeclaration(Schema p) {
         if (ModelUtils.isArraySchema(p)) {
             Schema inner = ModelUtils.getSchemaItems(p);
-            return ModelUtils.isSet(p) ? "Set<" + getTypeDeclaration(inner) + ">" : "[" + getTypeDeclaration(inner) + "]";
+            String innerTypeDeclaration = getItemsTypeDeclaration(inner);
+            return ModelUtils.isSet(p) ? "Set<" + innerTypeDeclaration + ">" : "[" + innerTypeDeclaration + "]";
         } else if (ModelUtils.isMapSchema(p)) {
             Schema inner = unaliasSchema(ModelUtils.getAdditionalProperties(p));
             return "[String: " + getItemsTypeDeclaration(inner) + "]";
@@ -825,7 +826,8 @@ public String getTypeDeclaration(Schema p) {
 
     private String getItemsTypeDeclaration(Schema items) {
         String itemsTypeDeclaration = getTypeDeclaration(items);
-        String nullable = items.getNullable() != null && items.getNullable() && !itemsTypeDeclaration.endsWith("?") ? "?" : "";
+        Schema itemsSchema = ModelUtils.getReferencedSchema(openAPI, unaliasSchema(items));
+        String nullable = ModelUtils.isNullable(itemsSchema) && !itemsTypeDeclaration.endsWith("?") ? "?" : "";
         return itemsTypeDeclaration + nullable;
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5ClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5ClientCodegenTest.java
index 8344a0427b76..ec64a91269d1 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5ClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5ClientCodegenTest.java
@@ -410,4 +410,35 @@ public void testAdditionalModelImportsParsing() {
         Assert.assertEquals(imports.get(2), "BazKit");
     }
 
+    @Test(description = "nullable array items are declared as optionals", enabled = true)
+    public void nullableArrayItemsTest() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/issue_22355.yaml");
+        final DefaultCodegen codegen = new Swift5ClientCodegen();
+        codegen.setOpenAPI(openAPI);
+        final String model = "NullItemsNotNullItems";
+        final CodegenModel cm = codegen.fromModel(model, openAPI.getComponents().getSchemas().get(model));
+
+        Assert.assertEquals(cm.vars.size(), 9);
+
+        Assert.assertEquals(cm.vars.get(0).baseName, "nullableItems");
+        Assert.assertEquals(cm.vars.get(1).baseName, "notNullableItems");
+        Assert.assertEquals(cm.vars.get(2).baseName, "defaultItems");
+        Assert.assertEquals(cm.vars.get(3).baseName, "nullableDoubleItems");
+        Assert.assertEquals(cm.vars.get(4).baseName, "xNullableItems");
+        Assert.assertEquals(cm.vars.get(5).baseName, "aliasedNullableItems");
+        Assert.assertEquals(cm.vars.get(6).baseName, "nullableItemsSet");
+        Assert.assertEquals(cm.vars.get(7).baseName, "nestedNullableItems");
+        Assert.assertEquals(cm.vars.get(8).baseName, "modelRefNullableItems");
+
+        Assert.assertEquals(cm.vars.get(0).dataType, "[String?]");
+        Assert.assertEquals(cm.vars.get(1).dataType, "[String]");
+        Assert.assertEquals(cm.vars.get(2).dataType, "[String]");
+        Assert.assertEquals(cm.vars.get(3).dataType, "[Double?]");
+        Assert.assertEquals(cm.vars.get(4).dataType, "[String?]");
+        Assert.assertEquals(cm.vars.get(5).dataType, "[String?]");
+        Assert.assertEquals(cm.vars.get(6).dataType, "Set<String?>");
+        Assert.assertEquals(cm.vars.get(7).dataType, "[[String?]]");
+        Assert.assertEquals(cm.vars.get(8).dataType, "[NullablePet?]");
+    }
+
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift6/Swift6ClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift6/Swift6ClientCodegenTest.java
index ad5ee6eb8c93..dfd3cd8796ac 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift6/Swift6ClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift6/Swift6ClientCodegenTest.java
@@ -505,4 +505,34 @@ public void testNullableMap() {
         Assert.assertEquals(notNullableMap.getDataType(), "[String: String]");
         Assert.assertEquals(defaultMap.getDataType(), "[String: String]");
     }
+
+    @Test(description = "Issue #22355")
+    public void testNullableArrayItems() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/swift6/issue22355-nullable-array-items.yaml");
+        final DefaultCodegen codegen = new Swift6ClientCodegen();
+        codegen.setOpenAPI(openAPI);
+
+        Schema test1 = openAPI.getComponents().getSchemas().get("NullItemsNotNullItems");
+        CodegenModel cm1 = codegen.fromModel("NullItemsNotNullItems", test1);
+
+        // Assert the dataType properly generated
+        CodegenProperty nullableItems = cm1.vars.get(0);
+        CodegenProperty notNullableItems = cm1.vars.get(1);
+        CodegenProperty defaultItems = cm1.vars.get(2);
+        CodegenProperty nullableDoubleItems = cm1.vars.get(3);
+        CodegenProperty xNullableItems = cm1.vars.get(4);
+        CodegenProperty aliasedNullableItems = cm1.vars.get(5);
+        CodegenProperty nullableItemsSet = cm1.vars.get(6);
+        CodegenProperty nestedNullableItems = cm1.vars.get(7);
+        CodegenProperty modelRefNullableItems = cm1.vars.get(8);
+        Assert.assertEquals(nullableItems.getDataType(), "[String?]");
+        Assert.assertEquals(notNullableItems.getDataType(), "[String]");
+        Assert.assertEquals(defaultItems.getDataType(), "[String]");
+        Assert.assertEquals(nullableDoubleItems.getDataType(), "[Double?]");
+        Assert.assertEquals(xNullableItems.getDataType(), "[String?]");
+        Assert.assertEquals(aliasedNullableItems.getDataType(), "[String?]");
+        Assert.assertEquals(nullableItemsSet.getDataType(), "Set<String?>");
+        Assert.assertEquals(nestedNullableItems.getDataType(), "[[String?]]");
+        Assert.assertEquals(modelRefNullableItems.getDataType(), "[NullablePet?]");
+    }
 }
diff --git a/modules/openapi-generator/src/test/resources/3_0/issue_22355.yaml b/modules/openapi-generator/src/test/resources/3_0/issue_22355.yaml
new file mode 100644
index 000000000000..ac92095767d5
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/issue_22355.yaml
@@ -0,0 +1,63 @@
+openapi: 3.0.0
+info:
+  title: 'Issue 22355 Nullable array items'
+  version: latest
+components:
+  schemas:
+    NullItemsNotNullItems:
+      properties:
+        nullableItems:
+          type: array
+          items:
+            type: string
+            nullable: true
+        notNullableItems:
+          type: array
+          items:
+            type: string
+            nullable: false
+        defaultItems:
+          type: array
+          items:
+            type: string
+        nullableDoubleItems:
+          type: array
+          items:
+            type: number
+            format: double
+            nullable: true
+        xNullableItems:
+          type: array
+          items:
+            type: string
+            x-nullable: true
+        aliasedNullableItems:
+          type: array
+          items:
+            $ref: '#/components/schemas/NullableString'
+        nullableItemsSet:
+          type: array
+          uniqueItems: true
+          items:
+            type: string
+            nullable: true
+        nestedNullableItems:
+          type: array
+          items:
+            type: array
+            items:
+              type: string
+              nullable: true
+        modelRefNullableItems:
+          type: array
+          items:
+            $ref: '#/components/schemas/NullablePet'
+    NullableString:
+      type: string
+      nullable: true
+    NullablePet:
+      type: object
+      nullable: true
+      properties:
+        name:
+          type: string
diff --git a/modules/openapi-generator/src/test/resources/3_0/swift6/issue22355-nullable-array-items.yaml b/modules/openapi-generator/src/test/resources/3_0/swift6/issue22355-nullable-array-items.yaml
new file mode 100644
index 000000000000..ac92095767d5
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/swift6/issue22355-nullable-array-items.yaml
@@ -0,0 +1,63 @@
+openapi: 3.0.0
+info:
+  title: 'Issue 22355 Nullable array items'
+  version: latest
+components:
+  schemas:
+    NullItemsNotNullItems:
+      properties:
+        nullableItems:
+          type: array
+          items:
+            type: string
+            nullable: true
+        notNullableItems:
+          type: array
+          items:
+            type: string
+            nullable: false
+        defaultItems:
+          type: array
+          items:
+            type: string
+        nullableDoubleItems:
+          type: array
+          items:
+            type: number
+            format: double
+            nullable: true
+        xNullableItems:
+          type: array
+          items:
+            type: string
+            x-nullable: true
+        aliasedNullableItems:
+          type: array
+          items:
+            $ref: '#/components/schemas/NullableString'
+        nullableItemsSet:
+          type: array
+          uniqueItems: true
+          items:
+            type: string
+            nullable: true
+        nestedNullableItems:
+          type: array
+          items:
+            type: array
+            items:
+              type: string
+              nullable: true
+        modelRefNullableItems:
+          type: array
+          items:
+            $ref: '#/components/schemas/NullablePet'
+    NullableString:
+      type: string
+      nullable: true
+    NullablePet:
+      type: object
+      nullable: true
+      properties:
+        name:
+          type: string