Add notes for useful Maestro techniques

.maestro/advanced-techniques.md

@@ -0,0 +1,52 @@
+[Cross platform techniques](https://blog.mobile.dev/best-practices-for-cross-platform-maestro-ui-testing-for-android-and-ios-98d1c471a838)
+
+## Platform specific init scripts
+
+Specify platform specific IDs.
+
+In a test.yaml
+
+```yaml
+- runScript:
+    when:
+      platform: iOS
+    file: ios/init.js
+
+#... more runScripts (for other platforms)
+
+- tapOn:
+    id: ${output.wallpapers.wallpaperItem}
+    index: 0
+```
+
+ios/init.js
+
+```js
+output.wallpapers = {
+    wallpaperItem: 'imageItem',
+}
+```
+
+## Run platform specific flows
+
+In a test.yaml this runs `Date.yaml` only on iOS. `Date.yaml` is expected to specify tests.
+
+```yaml
+- runFlow:
+    when:
+      platform: iOS
+    file: Date.yaml
+```
+
+See further down page on how to test platform share window.
+
+## Inline platform specific tests
+
+```yaml
+- runFlow:
+    when:
+      platform: Android
+    commands:
+      - assertVisible:
+          id: "setWallpaperIconButton"
+```