Setup an app variants folder and move the nightly and alpha build configs to it.

Variants/Alpha/Resources/Alpha.xcassets/AlphaAppIcon.appiconset/Contents.json

@@ -0,0 +1,14 @@
+{
+  "images" : [
+    {
+      "filename" : "AppIcon.png",
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Variants/Alpha/Resources/Alpha.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Variants/Alpha/alpha.yml

@@ -0,0 +1,11 @@
+settings:
+  BASE_APP_GROUP_IDENTIFIER: io.element.pr
+  BASE_BUNDLE_IDENTIFIER: io.element.elementx.pr
+
+targets:
+  ElementX:
+    settings:
+      base:
+        ASSETCATALOG_COMPILER_APPICON_NAME: AlphaAppIcon
+    sources:
+    - path: Resources

Variants/Nightly/Resources/Nightly.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Variants/Nightly/Resources/Nightly.xcassets/NightlyAppIcon.appiconset/Contents.json

@@ -0,0 +1,14 @@
+{
+  "images" : [
+    {
+      "filename" : "AppIcon.png",
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

Variants/Nightly/nightly.yml

@@ -0,0 +1,11 @@
+settings:
+  BASE_APP_GROUP_IDENTIFIER: io.element.nightly
+  BASE_BUNDLE_IDENTIFIER: io.element.elementx.nightly
+
+targets:
+  ElementX:
+    settings:
+      base:
+        ASSETCATALOG_COMPILER_APPICON_NAME: NightlyAppIcon
+    sources:
+    - path: Resources

fastlane/Fastfile

@@ -170,7 +170,7 @@ lane :config_nightly do |options|
 
   target_file_path = "../project.yml"
   data = YAML.load_file target_file_path
-  data["include"].append({ "path" => "fastlane/nightly.yml" })
+  data["include"].append({ "path" => "Variants/Nightly/nightly.yml" })
 
   config_secrets()
   
@@ -314,7 +314,7 @@ end
 private_lane :config_xcodegen_alpha do
   target_file_path = "../project.yml"
   data = YAML.load_file target_file_path
-  data["include"].append({ "path" => "fastlane/alpha.yml" })
+  data["include"].append({ "path" => "Variants/Alpha/alpha.yml" })
   File.open(target_file_path, 'w') { |f| YAML.dump(data, f) }
 
   xcodegen(spec: "project.yml")

fastlane/alpha.yml

@@ -1,3 +0,0 @@
-settings:
-  BASE_APP_GROUP_IDENTIFIER: io.element.pr
-  BASE_BUNDLE_IDENTIFIER: io.element.elementx.pr

fastlane/nightly.yml

@@ -1,3 +0,0 @@
-settings:
-  BASE_APP_GROUP_IDENTIFIER: io.element.nightly
-  BASE_BUNDLE_IDENTIFIER: io.element.elementx.nightly