Ensure that the top bar size is included in iOS layout calculations.

android/tests_backend/window.py

@@ -1,3 +1,4 @@
+from android.content import Context
 from androidx.appcompat import R as appcompat_R
 
 from .dialogs import DialogsMixin
@@ -20,6 +21,16 @@ def content_size(self):
             self.root_view.getHeight() / self.scale_factor,
         )
 
+    @property
+    def top_bar_height(self):
+        # Android doesn't require explicit allowances for the top bar in content layout;
+        # the size of the top bar is the difference between the screen and the root
+        # window content size.
+        context = self.app._impl.native.getApplicationContext()
+        window_manager = context.getSystemService(Context.WINDOW_SERVICE)
+        display = window_manager.getDefaultDisplay()
+        return (display.getHeight() - self.root_view.getHeight()) / self.scale_factor
+
     def _native_menu(self):
         return self.native.findViewById(appcompat_R.id.action_bar).getMenu()
 

changes/2836.bugfix.rst

@@ -0,0 +1 @@
+iOS apps now correctly account for the size of the navigation bar when laying out app content.

iOS/src/toga_iOS/container.py

@@ -78,7 +78,7 @@ def width(self):
 
     @property
     def height(self):
-        return self.layout_native.bounds.size.height
+        return self.layout_native.bounds.size.height - self.top_offset
 
     @property
     def top_offset(self):
@@ -149,11 +149,6 @@ def __init__(
         # Set the controller's view to be the root content widget
         self.controller.view = self.native
 
-    # The testbed app won't instantiate a simple app, so we can't test these properties
-    @property
-    def height(self):  # pragma: no cover
-        return self.layout_native.bounds.size.height - self.top_offset
-
     # The testbed app won't instantiate a simple app, so we can't test these properties
     @property
     def top_offset(self):  # pragma: no cover

iOS/tests_backend/window.py

@@ -30,5 +30,12 @@ def content_size(self):
             ),
         )
 
+    @property
+    def top_bar_height(self):
+        return (
+            UIApplication.sharedApplication.statusBarFrame.size.height
+            + self.native.rootViewController.navigationBar.frame.size.height
+        )
+
     def has_toolbar(self):
         pytest.skip("Toolbars not implemented on iOS")

testbed/tests/app/test_mobile.py

@@ -1,6 +1,8 @@
 import pytest
 
 import toga
+from toga.colors import REBECCAPURPLE
+from toga.style import Pack
 
 ####################################################################################
 # Mobile platform tests
@@ -9,6 +11,22 @@
     pytest.skip("Test is specific to desktop platforms", allow_module_level=True)
 
 
+async def test_content_size(app, main_window, main_window_probe):
+    """The content size doesn't spill outsize the viewable area."""
+
+    box = toga.Box(style=Pack(background_color=REBECCAPURPLE))
+    main_window.content = box
+
+    await main_window_probe.redraw("Content is a box")
+
+    # The overall layout has both the box, plus the top bar.
+    assert main_window.screen.size.height >= (
+        box.layout.content_height + main_window_probe.top_bar_height
+    )
+    # The box is the same width as the screen.
+    assert main_window.screen.size.width == box.layout.content_width
+
+
 async def test_show_hide_cursor(app):
     """The app cursor methods can be invoked"""
     # Invoke the methods to verify the endpoints exist. However, they're no-ops,