Fix multiplatform iOS builds

Gemfile.lock

@@ -44,7 +44,8 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    CFPropertyList (3.0.3)
+    CFPropertyList (3.0.6)
+      rexml
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     artifactory (3.0.15)
@@ -340,12 +341,13 @@ GEM
     xcode-install (2.6.8)
       claide (>= 0.9.1, < 1.1.0)
       fastlane (>= 2.1.0, < 3.0.0)
-    xcodeproj (1.19.0)
+    xcodeproj (1.22.0)
       CFPropertyList (>= 2.3.3, < 4.0)
       atomos (~> 0.1.3)
       claide (>= 1.0.2, < 2.0)
       colored2 (~> 3.1)
       nanaimo (~> 0.3.0)
+      rexml (~> 3.2.4)
     xcov (1.4.3)
       fastlane (>= 2.82.0, < 3.0.0)
       multipart-post

fastlane_core/lib/fastlane_core/project.rb

@@ -307,6 +307,10 @@ def watchos?
       supported_platforms.include?(:watchOS)
     end
 
+    def multiplatform?
+      supported_platforms.count > 1
+    end
+
     def supported_platforms
       supported_platforms = build_settings(key: "SUPPORTED_PLATFORMS")
       if supported_platforms.nil?

fastlane_core/spec/project_spec.rb

@@ -209,6 +209,10 @@ def within_a_temp_dir
         expect(@project.ios?).to eq(true)
       end
 
+      it "#multiplatform?", requires_xcode: true do
+        expect(@project.multiplatform?).to eq(false)
+      end
+
       it "#tvos?", requires_xcode: true do
         expect(@project.tvos?).to eq(false)
       end
@@ -250,6 +254,10 @@ def within_a_temp_dir
         expect(@project.tvos?).to eq(false)
       end
 
+      it "#multiplatform?", requires_xcode: true do
+        expect(@project.multiplatform?).to eq(false)
+      end
+
       it "schemes", requires_xcodebuild: true do
         expect(@project.schemes).to eq(["Mac"])
       end
@@ -273,6 +281,10 @@ def within_a_temp_dir
         expect(@project.tvos?).to eq(true)
       end
 
+      it "#multiplatform?", requires_xcode: true do
+        expect(@project.multiplatform?).to eq(false)
+      end
+
       it "schemes", requires_xcodebuild: true do
         expect(@project.schemes).to eq(["ExampleTVOS"])
       end
@@ -300,6 +312,10 @@ def within_a_temp_dir
         expect(@project.tvos?).to eq(true)
       end
 
+      it "#multiplatform?", requires_xcode: true do
+        expect(@project.multiplatform?).to eq(true)
+      end
+
       it "schemes", requires_xcodebuild: true do
         expect(@project.schemes).to eq(["CrossPlatformFramework"])
       end