Added ActivityIndicator implementation for iOS

changes/2829.feature.rst

@@ -0,0 +1 @@
+The ActivityIndicator widget is now supported on iOS.

docs/reference/api/widgets/activityindicator.rst

@@ -26,10 +26,11 @@ usually rendered as a "spinner" animation.
 
     Not supported
 
-  .. group-tab:: iOS |no|
-
-    Not supported
+  .. group-tab:: iOS
 
+    .. figure:: /reference/images/activityindicator-ios.png
+       :align: center
+       :width: 100px
   .. group-tab:: Web |beta|
 
     .. .. figure:: /reference/images/activityindicator-web.png

docs/reference/data/widgets_by_platform.csv

@@ -3,7 +3,7 @@ Application,Core Component,:class:`~toga.App`,The application itself,|y|,|y|,|y|
 Window,Core Component,:class:`~toga.Window`,An operating system-managed container of widgets.,|y|,|y|,|y|,|y|,|y|,|b|,|b|
 DocumentWindow,Core Component,:class:`~toga.DocumentWindow`,A window that can be used as the main interface to a document-based app.,|y|,|y|,|y|,,,,
 MainWindow,Core Component,:class:`~toga.MainWindow`,A window that can use the full set of window-level user interface elements.,|y|,|y|,|y|,|y|,|y|,|b|,|b|
-ActivityIndicator,General Widget,:class:`~toga.ActivityIndicator`,A spinning activity animation,|y|,|y|,,,,|b|,
+ActivityIndicator,General Widget,:class:`~toga.ActivityIndicator`,A spinning activity animation,|y|,|y|,,|y|,,|b|,
 Button,General Widget,:class:`~toga.Button`,Basic clickable Button,|y|,|y|,|y|,|y|,|y|,|b|,|b|
 Canvas,General Widget,:class:`~toga.Canvas`,A drawing area for 2D vector graphics.,|y|,|y|,|y|,|y|,|y|,,
 DateInput,General Widget,:class:`~toga.DateInput`,A widget to select a calendar date,,,|y|,,|y|,,

iOS/src/toga_iOS/factory.py

@@ -13,6 +13,7 @@
 from .statusicons import MenuStatusIcon, SimpleStatusIcon, StatusIconSet
 
 # Widgets
+from .widgets.activityindicator import ActivityIndicator
 from .widgets.box import Box
 from .widgets.button import Button
 from .widgets.canvas import Canvas
@@ -47,6 +48,7 @@ def not_implemented(feature):
 
 __all__ = [
     "not_implemented",
+    "ActivityIndicator",
     "App",
     "Command",
     # Resources

iOS/src/toga_iOS/libs/uikit.py

@@ -117,6 +117,10 @@ def NSTextAlignment(alignment):
 
 UIKeyInput = ObjCProtocol("UIKeyInput")
 
+######################################################################
+# UIActivityIndicatorView.h
+UIActivityIndicatorView = ObjCClass("UIActivityIndicatorView")
+
 ######################################################################
 # UIAlertController.h
 UIAlertController = ObjCClass("UIAlertController")

iOS/src/toga_iOS/widgets/activityindicator.py

@@ -0,0 +1,47 @@
+from rubicon.objc import CGSize
+
+from toga_iOS.libs import UIActivityIndicatorView, UIView
+from toga_iOS.widgets.base import Widget
+
+
+class ActivityIndicator(Widget):
+    def create(self):
+        """Implements the ActivityIndicator widget for iOS
+
+        Implementation note:
+        ===================
+
+        The UIActivityIndicatorView is added to a parent UIView because
+        there is an issue with the UIActivityIndicatorView's `hidesWhenStopped`
+        behavior - if it is not part of a parent UIView, the indicator
+        is immediately visible even when not animating, even when
+        `hidesWhenStopped` is set to `True`, but it works as expected when
+        it is added as a subview to a parent UIView.
+        """
+
+        self._activity_indicator = UIActivityIndicatorView.new()
+        self._activity_indicator.hidesWhenStopped = True
+        self._activity_indicator.translatesAutoresizingMaskIntoConstraints = False
+
+        self.native = UIView.new()
+        self.native.addSubview(self._activity_indicator)
+        self.native.translatesAutoresizingMaskIntoConstraints = False
+        self.native.sizeToFit()
+
+        self.add_constraints()
+
+    def is_running(self):
+        return self._activity_indicator.isAnimating()
+
+    def start(self):
+        self._activity_indicator.startAnimating()
+
+    def stop(self):
+        self._activity_indicator.stopAnimating()
+
+    def rehint(self):
+        fitting_size = self._activity_indicator.systemLayoutSizeFittingSize(
+            CGSize(0, 0)
+        )
+        self.interface.intrinsic.width = fitting_size.width
+        self.interface.intrinsic.height = fitting_size.height

iOS/tests_backend/widgets/activityindicator.py

@@ -0,0 +1,7 @@
+from toga_iOS.libs import UIView
+
+from .base import SimpleProbe
+
+
+class ActivityIndicatorProbe(SimpleProbe):
+    native_class = UIView

testbed/tests/widgets/test_activityindicator.py

@@ -11,7 +11,7 @@
 
 @pytest.fixture
 async def widget():
-    skip_on_platforms("android", "iOS", "windows")
+    skip_on_platforms("android", "windows")
     return toga.ActivityIndicator()