新增iOS混编示例代码

(cherry picked from commit f3924db7)

uni_modules/uts-tests/utssdk/NativeCode.uts

@@ -6,6 +6,9 @@ export function testNativeCode(): Result {
             // #ifdef APP-ANDROID
              expect(NativeCode.getNativeStr()).toEqual("android-code");
             // #endif
+            // #ifdef APP-IOS
+             expect(NativeCode.getNativeStr()).toEqual("iOS-code");
+            // #endif
         })
     })
 }

uni_modules/uts-tests/utssdk/app-ios/SwiftCode.swift

+import Foundation
+
+class NativeCode {
+    static func getNativeStr() -> String {
+        return "iOS-code"
+    }
+}