Flutter Engine
SemanticsObjectContainer Class Reference

#import <SemanticsObject.h>

Inheritance diagram for SemanticsObjectContainer:

Instance Methods

(instancetype) - NS_UNAVAILABLE
 
(instancetype) - initWithAccessibilityContainer:
 
(instancetype) - initWithSemanticsObject:bridge:
 

Class Methods

(instancetype) + NS_UNAVAILABLE
 

Properties

SemanticsObjectsemanticsObject
 

Detailed Description

Represents a semantics object that has children and hence has to be presented to the OS as a UIAccessibilityContainer.

The SemanticsObject class cannot implement the UIAccessibilityContainer protocol because an object that returns YES for isAccessibilityElement cannot also implement UIAccessibilityContainer.

With the help of SemanticsObjectContainer, the hierarchy of semantic objects received from the framework, such as:

SemanticsObject1 SemanticsObject2 SemanticsObject3 SemanticsObject4

is translated into the following hierarchy, which is understood by iOS:

SemanticsObjectContainer1 SemanticsObject1 SemanticsObjectContainer2 SemanticsObject2 SemanticsObject3 SemanticsObject4

From Flutter's view of the world (the first tree seen above), we construct iOS's view of the world (second tree) as follows: We replace each SemanticsObjects that has children with a SemanticsObjectContainer, which has the original SemanticsObject and its children as children.

SemanticsObjects have semantic information attached to them which is interpreted by VoiceOver (they return YES for isAccessibilityElement). The SemanticsObjectContainers are just there for structure and they don't provide any semantic information to VoiceOver (they return NO for isAccessibilityElement).

Definition at line 193 of file SemanticsObject.h.

Method Documentation

◆ initWithAccessibilityContainer:()

- (instancetype) initWithAccessibilityContainer: (id NS_UNAVAILABLE

◆ initWithSemanticsObject:bridge:()

- (instancetype) initWithSemanticsObject: (SemanticsObject*)  semanticsObject
bridge: (fml::WeakPtr<flutter::AccessibilityBridgeIos>)  NS_DESIGNATED_INITIALIZER 

Definition at line 611 of file SemanticsObject.mm.

References _bridge, FML_DCHECK, SemanticsObject::hasChildren, id, FlutterPlatformViewSemanticsContainer::index, flutter::SemanticsNode::IsPlatformViewNode(), kRootNodeId, SemanticsObject::node, SemanticsObject::platformViewSemanticsContainer, semanticsObject, and flutter::AccessibilityBridgeIos::view().

611  :(SemanticsObject*)semanticsObject
613  FML_DCHECK(semanticsObject) << "semanticsObject must be set";
614  // Initialize with the UIView as the container.
615  // The UIView will not necessarily be accessibility parent for this object.
616  // The bridge informs the OS of the actual structure via
617  // `accessibilityContainer` and `accessibilityElementAtIndex`.
618  self = [super initWithAccessibilityContainer:bridge->view()];
619 
620  if (self) {
621  _semanticsObject = semanticsObject;
622  _bridge = bridge;
623  }
624 
625  return self;
626 }
fml::WeakPtr< flutter::AccessibilityBridgeIos > _bridge
#define FML_DCHECK(condition)
Definition: logging.h:86
SemanticsObject * semanticsObject

◆ NS_UNAVAILABLE() [1/2]

- (instancetype) NS_UNAVAILABLE

◆ NS_UNAVAILABLE() [2/2]

+ (instancetype) NS_UNAVAILABLE

Property Documentation

◆ semanticsObject

- (SemanticsObject*) semanticsObject
readwritenonatomicweak

Definition at line 201 of file SemanticsObject.h.

Referenced by initWithSemanticsObject:bridge:.


The documentation for this class was generated from the following files: