GARSession

ARCore session class.

Summary

Adds ARCore features to an app using ARKit. All NSError's returned by methods in this class have domain GARSessionErrorDomain and code a value of GARSessionErrorCode. For Augmented Faces, see GARAugmentedFaceSession. See categories of this class for other features. Each feature must be turned on by using setConfiguration:error: (GARSession) prior to use.

Inheritance

Inherits from: NSObject

Properties

currentFramePair
The most recent frame pair, containing the most recent ARFrame passed into update:error: and the corresponding returned GARFrame.
delegate
The delegate for receiving callbacks about the GARSession.
delegateQueue
dispatch_queue_t
The dispatch queue on which the delegate receives calls.

Public static methods

sessionWithAPIKey:bundleIdentifier:error:
nullable instancetype
Creates a GARSession with an API key and bundle identifier.
sessionWithError:
nullable instancetype
Creates a GARSession.

Public methods

checkVPSAvailabilityAtCoordinate:completionHandler:
Gets the availability of the Visual Positioning System (VPS) at a specified horizontal position.
createAnchorWithCoordinate:altitude:eastUpSouthQAnchor:error:
nullable GARAnchor *
Creates a Geospatial anchor at the specified geodetic location and orientation relative to the Earth.
createAnchorWithCoordinate:altitudeAboveTerrain:eastUpSouthQAnchor:error:
nullable GARAnchor *
Creates a Terrain anchor at the specified geodetic location, altitude relative to the horizontal position’s terrain and orientation relative to the Earth.
estimateFeatureMapQualityForHosting:error:
Estimates the quality of the visual features seen by ARCore in the preceding few seconds and visible from the provided camera transform.
geospatialTransformFromTransform:error:
Converts the provided transform to a GARGeospatialTransform with respect to the Earth.
hostCloudAnchor:TTLDays:error:
nullable GARAnchor *
This will create a new Cloud Anchor with a given lifetime in days, using the transform of the provided anchor.
hostCloudAnchor:error:
nullable GARAnchor *
Hosts a new Cloud Anchor based on an ARAnchor.
isGeospatialModeSupported:
BOOL
Determines whether the given geospatial mode is supported on the current device and OS version.
removeAnchor:
void
Removes an anchor from the session.
resolveCloudAnchorWithIdentifier:error:
nullable GARAnchor *
Resolves a Cloud Anchor with a given identifier.
setAuthToken:
void
Provide an auth token to use when authenticating with Google Cloud Services.
setConfiguration:error:
void
Sets the configuration for the session.
transformFromGeospatialCoordinate:altitude:eastUpSouthQTarget:error:
matrix_float4x4
Converts the provided Earth specified horizontal position, altitude and rotation with respect to an east-up-south coordinate frame to a local transform in world coordinate space.
update:error:
nullable GARFrame *
Updates the GARSession with an ARFrame.

Properties

currentFramePair

@property(atomic, readonly, nullable) GARFramePair *currentFramePair;

The most recent frame pair, containing the most recent ARFrame passed into update:error: and the corresponding returned GARFrame.

delegate

@property(atomic, weak, nullable) id delegate;

The delegate for receiving callbacks about the GARSession.

delegateQueue

@property(atomic, nullable) dispatch_queue_t delegateQueue;

The dispatch queue on which the delegate receives calls.

If nil, callbacks happen on the main thread.

Public static methods

sessionWithAPIKey:bundleIdentifier:error:

+ (nullable instancetype)sessionWithAPIKey:
(NSString *) apiKey
bundleIdentifier:
(nullable NSString *) bundleIdentifier
error:
(NSError **) error

Creates a GARSession with an API key and bundle identifier.

Details
Parameters
apiKey
Your API key for Google Cloud Services.
bundleIdentifier
The bundle identifier associated to your API key. If nil, defaults to [[NSBundle mainBundle] bundleIdentifier].
error
Out parameter for an NSError. Possible errors:
Returns
The new GARSession, or nil if there is an error.

sessionWithError:

+ (nullable instancetype)sessionWithError:
(NSError **) error

Creates a GARSession.

To authenticate with Google Cloud Services, use setAuthToken:.

Details
Parameters
error
Out parameter for an NSError. Possible errors:
Returns
The new GARSession, or nil if there is an error.

Public methods

checkVPSAvailabilityAtCoordinate:completionHandler:

- (GARVPSAvailabilityFuture *)checkVPSAvailabilityAtCoordinate:
(CLLocationCoordinate2D) coordinate
completionHandler:
(void(^)(GARVPSAvailability availability)) completionHandler

Gets the availability of the Visual Positioning System (VPS) at a specified horizontal position.

The availability of VPS in a given location helps to improve the quality of Geospatial localization and tracking accuracy.

This launches an asynchronous operation used to query the Google Cloud ARCore API. This function returns a GARVPSAvailabilityFuture which can be used to obtain the task's result. Its initial GARFutureState will be set to GARFutureStatePending. When the operation is completed, its GARFutureState will be set to GARFutureStateDone, and GARVPSAvailabilityFuture.state can be used to obtain the operation's result.

You may provide an optional completionHandler, which will be invoked when the operation is completed, unless the GARVPSAvailabilityFuture has been cancelled. The callback will be called on the Main thread.

Your app must be properly set up to communicate with the Google Cloud ARCore API in order to obtain a result from this call. See Check VPS Availability for more details on setup steps and usage examples.

Details
Parameters
coordinate
The coordinate at which to check availability.
completionHandler
Completion handler to be invoked on the Main thread, if not nil.
Returns
A handler that can be polled or cancelled. If the operation is cancelled, no callback will be invoked.
Provided by category GARSession(Geospatial).

createAnchorWithCoordinate:altitude:eastUpSouthQAnchor:error:

- (nullable GARAnchor *)createAnchorWithCoordinate:
(CLLocationCoordinate2D) coordinate
altitude:
(CLLocationDistance) altitude
eastUpSouthQAnchor:
(simd_quatf) eastUpSouthQAnchor
error:
(NSError **) error

Creates a Geospatial anchor at the specified geodetic location and orientation relative to the Earth.

Latitude and longitude are defined by the WGS84 specification, and altitude values are defined as the elevation above the WGS84 ellipsoid in meters.

The rotation provided by eastUpSouthQAnchor is a rotation with respect to an east-up-south coordinate frame. An identity rotation will have the anchor oriented such that X+ points to the east, Y+ points up away from the center of the earth, and Z+ points to the south.

An anchor's GARAnchor.trackingState will be GARTrackingStatePaused while GAREarth is GARTrackingStatePaused. The tracking state will permanently become GARTrackingStateStopped if the GARSession configuration is set to GARGeospatialModeDisabled.

Creating anchors near the north pole or south pole is not supported. If the latitude is within 0.1° of the north pole or south pole (90° or -90 °), this function will output GARSessionErrorCodeInvalidArgument and the anchor will fail to be created.

Details
Parameters
coordinate
The latitude and longitude associated with the location, specified using the WGS84 reference frame. This must not be within .1° of the North or South pole (i.e. +- 90°).
altitude
Altitude in reference to the WGS 84 ellipsoid, in meters. Positive values indicate altitudes above approximate sea level. Negative values indicate altitudes below approximate sea level.
eastUpSouthQAnchor
Represents the quaternion from the anchor to East-Up-South (EUS) coordinates (i.e., +X points East, +Y points up, and +Z points South).
error
Out param for an NSError. Possible error codes:
Returns
The new anchor, or nil if there was an error.
Provided by category GARSession(Geospatial).

createAnchorWithCoordinate:altitudeAboveTerrain:eastUpSouthQAnchor:error:

- (nullable GARAnchor *)createAnchorWithCoordinate:
(CLLocationCoordinate2D) coordinate
altitudeAboveTerrain:
(CLLocationDistance) altitudeAboveTerrain
eastUpSouthQAnchor:
(simd_quatf) eastUpSouthQAnchor
error:
(NSError **) error

Creates a Terrain anchor at the specified geodetic location, altitude relative to the horizontal position’s terrain and orientation relative to the Earth.

Terrain means the ground, or ground floor inside a building with VPS coverage.

The specified altitudeAboveTerrain is interpreted to be relative to the Earth's terrain (or floor) at the specified latitude/longitude geodetic coordinates, rather than relative to the WGS-84 ellipsoid. Specifying an altitudeAboveTerrain of 0 will position the anchor directly on the terrain (or floor) whereas specifying a positive altitudeAboveTerrain will position the anchor above the terrain (or floor), against the direction of gravity.

This function schedules a task to resolve the anchor's pose using the given parameters. You may resolve multiple anchors at a time, but a session cannot be tracking more than 100 Terrain anchors at time. Attempting to resolve more than 100 Terrain anchors will result in GARSessionErrorCodeResourceExhausted.

If this function returns error nil, the terrain anchor's GARAnchor.terrainState will be GARTerrainAnchorStateTaskInProgress, and its tracking state will be GARTrackingStatePaused. This anchor remains in this state until its pose has been successfully resolved. If the resolving task results in an error, the tracking state will be set to GARTrackingStateStopped.

Latitude and longitude are defined by the WGS84 specification, and altitude values are defined as the elevation above the WGS84 ellipsoid in meters.

The rotation provided by eastUpSouthQAnchor is a rotation with respect to an east-up-south coordinate frame. An identity rotation will have the anchor oriented such that X+ points to the east, Y+ points up away from the center of the earth, and Z+ points to the south.

An anchor's GARAnchor.trackingState will be GARTrackingStateTracking while GAREarth is GARTrackingStatePaused. The tracking state will permanently become GARTrackingStateStopped if the GARSession configuration is set to GARGeospatialModeDisabled.

Creating anchors near the north pole or south pole is not supported. If the latitude is within 0.1° of the north pole or south pole (90° or -90°), this function will output GARSessionErrorCodeInvalidArgument and the anchor will fail to be created.

Details
Parameters
coordinate
The latitude and longitude associated with the location, specified using the WGS84 reference frame. This must not be within .1° of the North or South pole (i.e. +- 90°).
altitudeAboveTerrain
Altitude above Earth's terrain, in meters.
eastUpSouthQAnchor
Represents the quaternion from the anchor to East-Up-South (EUS) coordinates (i.e., +X points East, +Y points up, and +Z points South).
error
Out param for an NSError. Possible error codes:
Returns
The new anchor, or nil if there was an error.
Provided by category GARSession(Geospatial).

estimateFeatureMapQualityForHosting:error:

- (GARFeatureMapQuality)estimateFeatureMapQualityForHosting:
(simd_float4x4) transform
error:
(NSError **) error

Estimates the quality of the visual features seen by ARCore in the preceding few seconds and visible from the provided camera transform.

Cloud Anchors hosted using higher quality features will generally result in easier and more accurately resolved Cloud Anchor transforms.

Details
Parameters
transform
The camera transform to use in estimating the quality.
error
Out parameter for an NSError. Possible errors:
Returns
The estimated quality of the visual features seen by ARCore in the preceding few seconds and visible from the provided camera transform.
Provided by category GARSession(CloudAnchors).

geospatialTransformFromTransform:error:

- (nullable GARGeospatialTransform *)geospatialTransformFromTransform:
(matrix_float4x4) transform
error:
(NSError **) error

Converts the provided transform to a GARGeospatialTransform with respect to the Earth.

Its heading will be zero for a GARGeospatialTransform returned from this method.

Details
Parameters
transform
The local transform in world coordinate space.
error
Out param for an NSError. Possible error codes:
Returns
GARGeospatialTransform, or nil if there was an error.
Provided by category GARSession(Geospatial).

hostCloudAnchor:TTLDays:error:

- (nullable GARAnchor *)hostCloudAnchor:
(ARAnchor *) anchor
TTLDays:
(NSInteger) TTLDays
error:
(NSError **) error

This will create a new Cloud Anchor with a given lifetime in days, using the transform of the provided anchor.

The cloud state of the returned anchor will be set to GARCloudAnchorStateTaskInProgress and the initial transform will be set to the transform of the provided anchor. However, the returned anchor is completely independent of the original anchor, and the two transforms might diverge over time.

Hosting requires an active session for which the tracking state is ARTrackingStateNormal, as well as a working internet connection. ARCore will continue to retry silently in the background if it is unable to establish a connection to the ARCore API service.

Details
Parameters
anchor
The ARAnchor with the desired transform to be used to create a hosted Cloud Anchor.
TTLDays
The lifetime of the anchor in days. Must be positive. The maximum allowed value is 1 if using an API Key to authenticate with the ARCore API service, otherwise the maximum allowed value is 365.
error
Out parameter for an NSError. Possible errors:
Returns
The new GARAnchor, or nil if there is an error.
Provided by category GARSession(CloudAnchors).

hostCloudAnchor:error:

- (nullable GARAnchor *)hostCloudAnchor:
(ARAnchor *) anchor
error:
(NSError **) error

Hosts a new Cloud Anchor based on an ARAnchor.

The new anchor will have a cloud state of GARCloudAnchorStateTaskInProgress and its initial transform will be set to that of the passed-in anchor. However, the two transforms may differ over time.

Details
Parameters
anchor
The ARAnchor to host.
error
Out parameter for an NSError. Possible errors:
Returns
The new GARAnchor, or nil if there is an error.
Provided by category GARSession(CloudAnchors).

isGeospatialModeSupported:

- (BOOL)isGeospatialModeSupported:
(GARGeospatialMode) geospatialMode

Determines whether the given geospatial mode is supported on the current device and OS version.

If this returns NO, then configuring the session with the given geospatial mode will fail with the error code GARSessionErrorCodeConfigurationNotSupported. A device may be incompatible with a given mode due to insufficient sensor capabilities.

Details
Parameters
geospatialMode
The Geospatial mode.
Returns
YES if the geospatialMode is supported, NO otherwise.
Provided by category GARSession(Geospatial).

removeAnchor:

- (void)removeAnchor:
(GARAnchor *) anchor

Removes an anchor from the session.

Details
Parameters
anchor
The anchor to remove.

resolveCloudAnchorWithIdentifier:error:

- (nullable GARAnchor *)resolveCloudAnchorWithIdentifier:
(NSString *) identifier
error:
(NSError **) error

Resolves a Cloud Anchor with a given identifier.

The new anchor is immediately added to the session and returned, but without a valid transform. You don’t need to wait for a call to resolve a Cloud Anchor to complete before initiating another call. A session can be resolving up to 40 Cloud Anchors at a given time. If resolving fails, the anchor will be automatically removed from the session.

Details
Parameters
identifier
The Cloud Anchor identifier for the anchor.
error
Out parameter for an NSError. Possible errors:
Returns
The new GARAnchor, or nil if there is an error.
Provided by category GARSession(CloudAnchors).

setAuthToken:

- (void)setAuthToken:
(NSString *) authToken

Provide an auth token to use when authenticating with Google Cloud Services.

If the session was created with an API Key, the token will be ignored and an error will be logged. Otherwise, the most recent valid auth token passed in will be used. Call this method each time you refresh your token.

Details
Parameters
authToken
Token to use when authenticating with Google Cloud Services. This must be a nonempty ASCII string with no spaces or control characters. This will be used until another token is passed in. See documentation for supported token types.

setConfiguration:error:

- (void)setConfiguration:
(GARSessionConfiguration *) configuration
error:
(NSError **) error

Sets the configuration for the session.

Details
Parameters
configuration
The new configuration to use.
error
Out param for an NSError.

transformFromGeospatialCoordinate:altitude:eastUpSouthQTarget:error:

- (matrix_float4x4)transformFromGeospatialCoordinate:
(CLLocationCoordinate2D) coordinate
altitude:
(CLLocationDistance) altitude
eastUpSouthQTarget:
(simd_quatf) eastUpSouthQTarget
error:
(NSError **) error

Converts the provided Earth specified horizontal position, altitude and rotation with respect to an east-up-south coordinate frame to a local transform in world coordinate space.

Details
Parameters
coordinate
The latitude and longitude associated with the location, specified using the WGS84 reference frame. This must not be within .1° of the North or South pole (i.e. +- 90°).
altitude
Altitude in reference to the WGS 84 ellipsoid, in meters. Positive values indicate altitudes above approximate sea level. Negative values indicate altitudes below approximate sea level.
eastUpSouthQTarget
Represents the quaternion from the target to East-Up-South (EUS) coordinates (i.e., +X points East, +Y points up, and +Z points South).
error
Out param for an NSError. Possible error codes:
Returns
a local transform in world coordinate space.
Provided by category GARSession(Geospatial).

update:error:

- (nullable GARFrame *)update:
(ARFrame *) frame
error:
(NSError **) error

Updates the GARSession with an ARFrame.

Call this method with every ARFrame to keep the sessions synced. Can be called on any thread. Normally, this should be called from your ARSessionDelegate's session:didUpdateFrame: method.

Details
Parameters
frame
The next ARFrame from ARKit.
error
Out parameter for NSError. Possible errors:
Returns
The GARFrame corresponding to the ARFrame passed in, or nil if there is an error.