AGSGroupLayer Class Reference

Description

A container for other layers and group layers. It is used to represent datasets that are composed of multiple layers to be managed as a single layer with respect to display in a map or scene.

Group layers are designed for presentation of operational layers that are related by a theme. You can add several related operational child layers into a group layer so the layers can be displayed together. Suppose there are several feature layers that represent existing infrastructure projects (buildings, sidewalks, roads, and trees). You can add these feature layers into a single group layer called "Existing". Similarly assume there are also proposed infrastructure projects that are features in other layers. These layers can be added to a group layer called "Planned". You can manage the visibility of the existing or planned features as separate groups.

For the most part, group layers behave like any other layer in that:

• A group layer has visual properties (visibility, opacity) that can be applied to all layers in the group layer at once. This is helpful when controlling the visibility of the group.
• You can set a scale range on a group layer using the minimum and maximum scale properties. If a child layer has more restricted scale range, that scale range will be honored for that child layer.
• A group layer may be queried for the aggregate geographic extent of its child layers
• A group layer may be nested inside another group layer. There is no defined nesting level limit.
• Cloning a group layer will also clone its child layers
• A group layer does not have its own attribute values. The text from the child layers is displayed instead.
• A group layer is not time-aware, but may contain layers that are
• A group layer cannot be added to a basemap

The full extent of a group layer is derived asynchronously based on what information is available from the child layers. This means the full extent can change when child layers are added or removed. The full extent geometry will have the spatial reference of the first loaded child layer.

Group layers are not supported in web maps. Saving a map with a group layer to a web map flattens the operational layers. Group layers are supported in web scenes. The visual opacity property of the group layer affects the opacity of the child layers. The opacity of the child layers is a mathematical product of the individual child layer's opacity and the group layer's opacity. Opacity values range from 0.0 (transparent) to 1.0 (opaque). This means that setting the opacity of the group layer to 0.0 will make all child layers transparent [0 * AnyNumber = 0]. Likewise when the group layer opacity is 1.0, will set the opacity of the child layers to their individual layer opacity [1 * AnyNumber = AnyNumber].

See also

AGSLayer

Since

100.5

Inheritance diagram for AGSGroupLayer:

Instance Methods
(void)	- cancelLoad
(void)	- doCancelLoading
(void)	- doStartLoading:
(id< AGSCancelable >)	- fetchLegendInfosWithCompletion:
(instancetype)	- initWithChildLayers:
(BOOL)	- isEqualToLayer:
(BOOL)	- isVisibleAtScale:
(void)	- loadDidFinishWithError:
(void)	- loadWithCompletion:
(void)	- onLoadStatusChanged
(void)	- retryLoadWithCompletion:

Class Methods
(instancetype)	+ groupLayer
(instancetype)	+ groupLayerWithChildLayers:

Properties
NSString *	attribution
BOOL	canChangeVisibility
AGSEnvelope *	fullExtent
BOOL	identifyEnabled
AGSItem *	item
NSString *	layerDescription
NSString *	layerID
NSMutableArray< AGSLayer * > *	layers
NSError *	loadError
AGSLoadStatus	loadStatus
double	maxScale
double	minScale
NSString *	name
float	opacity
BOOL	showChildrenInLegend
BOOL	showInLegend
AGSSpatialReference *	spatialReference
NSArray< id< AGSLayerContent > > *	subLayerContents
void(^	subLayerContentsChangedHandler )(void)
AGSGroupVisibilityMode	visibilityMode
BOOL	visible

Method Documentation

cancelLoad

- (void) cancelLoad

requiredinherited

Cancels loading if it is in progress, otherwise it does nothing. This should be called carefully because other objects could be waiting for loadWithCompletion: or retryLoadWithCompletion: to complete and this will call them all back with the error of NSUserCancelledError

Since

100

doCancelLoading

- (void) doCancelLoading

Never call this method directly. The framework calls this method on a background thread when cancelLoad (AGSLoadable-p) is called. It is meant to be overriden by subclasses. Subclasses should override this method to cancel loading their data and call loadDidFinishWithError: (AGSLoadableBase(ForSubclassEyesOnly)) at the end passing in an error representing NSUserCancelledError.

Since

100

Provided by category AGSLoadableBase(ForSubclassEyesOnly).

doStartLoading:

- (void) doStartLoading:

(BOOL)

retrying

Never call this method directly. The framework calls this method on a background thread when loadWithCompletion: (AGSLoadable-p) or retryLoadWithCompletion: (AGSLoadable-p) is called. It is meant to be overriden by subclasses. Subclasses should override this method to load their data and call loadDidFinishWithError: (AGSLoadableBase(ForSubclassEyesOnly)) upon completion, passing in the error if any.

Parameters

retrying

flag that is true if this method was called from retryLoadWithCompletion: (AGSLoadable-p).

Since

100

Provided by category AGSLoadableBase(ForSubclassEyesOnly).

fetchLegendInfosWithCompletion:

- (id<AGSCancelable>) fetchLegendInfosWithCompletion:

(void(^)(NSArray< AGSLegendInfo * > *__nullable legendInfos, NSError *__nullable error))

completion

Fetches the array of legend infos (AGSLegendInfo) for this layer.

Since

100

groupLayer

+ (instancetype) groupLayer

Creates a layer. Once the layer is created you will have to set the child layers by setting the AGSGroupLayer::layers property.

Returns

A new group layer object.

Since

100.5

groupLayerWithChildLayers:

+ (instancetype) groupLayerWithChildLayers:

(NSArray< AGSLayer * > *)

childLayers

Creates a layer with child layers.

Parameters

childLayers

An array of layers to combine into a group layer.

Returns

A new group layer object.

See also

AGSGroupLayer::layers

Since

100.5

initWithChildLayers:

- (instancetype) initWithChildLayers:

(NSArray< AGSLayer * > *)

childLayers

Creates a layer with child layers.

Parameters

childLayers

An array of layers to combine into a group layer.

See also

AGSGroupLayer::layers

Since

100.5

isEqualToLayer:

- (BOOL) isEqualToLayer:

(AGSLayer *)

other

isVisibleAtScale:

- (BOOL) isVisibleAtScale:

(double)

scale

Check whether this layer is visible at a given scale.

Since

100

loadDidFinishWithError:

- (void) loadDidFinishWithError:

(nullable NSError *)

error

Only subclasses should call this method in doStartLoading: (AGSLoadableBase(ForSubclassEyesOnly)) and doCancelLoading (AGSLoadableBase(ForSubclassEyesOnly)) when done loading or failed to load.

Since

100

Provided by category AGSLoadableBase(ForSubclassEyesOnly).

loadWithCompletion:

- (void) loadWithCompletion: (nullable void(^)(NSError *__nullable error))  completion

requiredinherited

Loads data for the object asynchronously. The completion block is invoked upon completion.

You can call this method any number of times, however only one attempt is made to load the data. If it is already loading, it will just continue to load (i.e. not force a reload). If it has already loaded successfully, the completion block will be invoked right away. If it has already failed to load, the completion block will be invoked right away with error previously encountered. This method supports multiple callers and will call them all back on completion. However, each caller's completion block will be invoked once and only once.

Parameters

completion

block that is invoked when object loads successfully or fails to load. An error is passed to the block if the object fails to load.

Note

The completion block is always invoked on the main thread.

Since

100

See also

- cancelLoad to cancel loading

- retryLoadWithCompletion: to force reload

onLoadStatusChanged

- (void) onLoadStatusChanged

Never call this method directly. The framework calls this method on a background thread when AGSLoadable::loadStatus changes is called. Subclasses can optionally implement this to know when their loading status has changed.

Since

100

Provided by category AGSLoadableBase(ForSubclassEyesOnly).

retryLoadWithCompletion:

- (void) retryLoadWithCompletion: (nullable void(^)(NSError *__nullable error))  completion

requiredinherited

Tries to reload when an object has failed to load. This method should be called judiciously. It should be called when:

1. you didn't have network connectivity earlier when it failed and you want to retry now that you have connectivity
2. the server was down earlier when it failed and you want to retry
3. the request is taking too long and you want to cancel it and retry, in which case you will first call cancelLoad and then this method

If the data hasn't started loading, it will start loading. If it is already loading, it will just continue to load. If it has already loaded successfully, calls back right away. If it has already failed to load, tries again. This method supports multiple callers and will call them all back on completion. However, each caller's completion block will be invoked once and only once.

Parameters

completion

block that is invoked when object loads successfully or fails to load. An error is passed to the block if the object fails to load.

Note

The completion block is always invoked on the main thread.

Since

100

Property Documentation

attribution

- (NSString*) attribution

readnonatomiccopyinherited

Attribution information of the layer.

Since

100

canChangeVisibility

- (BOOL) canChangeVisibility

readrequirednonatomicassigninherited

Denotes whether the layer can change visibility or not.

Since

100

fullExtent

- (AGSEnvelope*) fullExtent

readnonatomicstronginherited

Full extent of the layer.

Since

100

identifyEnabled

- (BOOL) identifyEnabled

readnonatomicassigninherited

Specifies whether the layer supports identify.

Since

100

item

- (AGSItem*) item

readnonatomicstronginherited

The item the layer has been created from.

Since

100

layerDescription

- (NSString*) layerDescription

readwritenonatomiccopyinherited

The layer's description.

Since

100

layerID

- (NSString*) layerID

readwritenonatomiccopyinherited

The layer's ID specified in the web map item of ArcGIS Online or an on-premises portal.

Since

100

layers

- (NSMutableArray<AGSLayer *>*) layers

readnonatomicstrong

The child layers nested within this group layer.

Note

This array does not allow duplicate objects.

Since

100.5

loadError

- (NSError*) loadError

readnonatomicstronginherited

The error that was encountered during the most recent load operation. Will be nil if the operation succeeded.

Since

100

loadStatus

- (AGSLoadStatus) loadStatus

readrequirednonatomicassigninherited

Status of the load operation.

Since

100

maxScale

- (double) maxScale

readwritenonatomicassigninherited

The maximum scale at which this layer is visible. If the map or scene is zoomed in beyond this scale, the layer will not be visible. A value of 0 means there is no maximum scale threshold and the layer will be visible at the smallest scale available for the map or scene.

Since

100

minScale

- (double) minScale

readwritenonatomicassigninherited

The minimum scale at which this layer is visible. If the map or scene is zoomed out. beyond this scale, the layer will not be visible. A value of 0 means there is no minimum scale threshold and the layer will be visible at the largest scale available for the map or scene.

Since

100

name

- (NSString*) name

readwritenonatomiccopyinherited

The name of the layer.

Since

100

opacity

- (float) opacity

readwritenonatomicassigninherited

The opacity of this layer as a value between 0 (fully transparent) and 1 (fully opaque). Default value is 1.

Since

100

showChildrenInLegend

- (BOOL) showChildrenInLegend

readwritenonatomicassign

Determines if the child layers should be shown in the map legend.

Since

100.5

showInLegend

- (BOOL) showInLegend

readwritenonatomicassigninherited

Indicates whether to show legend information.

Since

100

spatialReference

- (AGSSpatialReference*) spatialReference

readnonatomicstronginherited

The spatial reference of the layer.

Since

100

subLayerContents

- (NSArray<id<AGSLayerContent> >*) subLayerContents

readnonatomiccopyinherited

This layer's sub-layers.

Since

100

subLayerContentsChangedHandler

- (void(^ subLayerContentsChangedHandler) (void))

readwritenonatomiccopyinherited

Block that is invoked when the sub layer contents changes.

Note

The block will be invoked on the same thread on which the event occurred, which could be any arbitrary thread. You need to dispatch any UI related work to the main thread.

Since

100

visibilityMode

- (AGSGroupVisibilityMode) visibilityMode

readwritenonatomicassign

The visibility mode for the layers in a table of contents.

Since

100.9

visible

- (BOOL) visible

readwritenonatomicassigninherited

Denotes whether the layer is visible or not. The visibility changes can be monitored using Key-Value Observing (KVO).

Since

100