AGSKMLLayer Class Reference

Description

A layer that can visualize KML data.

Keyhole Markup Language (KML) is a specification for working with geographic content. KML files can contain 2D and 3D content, as well as links to content from the network. ArcGIS Runtime provides the ability to read .kml and .kmz files from disk or the network. You can also create, edit, and save a KML layer via the AGSKMLDataset.

Functional characteristics KML represents features as a tree of nodes, including network links, folders, and place marks. Like ArcGIS features, place marks are defined with point, line, or polygon geometry. KML geometry, however, is always based on the WGS84 coordinate system. KML can also have attributes, but unlike ArcGIS feature services, a KML document does not use a schema to define a standard set of fields. ArcGIS Runtime supports version 2.2 of the KML specification as defined by the Open Geospatial Consortium (OGC).

Unique features of KML include network links and screen overlays. Network links are useful for retrieving network content on a specified interval—perfect for keeping a live map up to date. Network links can also be used to split a large KML file into multiple per-region KML files, with each being loaded only when the region is in view. Screen overlays can be used to show content, such as branding or a legend, on top of the view. Screen overlay content does not scroll with the map or react to user interaction.

All coordinates are expressed in latitude and longitude (using decimal degrees), and are based on the WGS84 (AGSSpatialReference) geographic coordinate system. Altitude is always expressed in meters. The geographic features can contain attribute information and various styles can be specified to render them. Ground overlays allow images to be displayed for specific geographic objects or draped onto the map itself. Screen overlays allow fixing images to the AGSGeoView, and may be used for compasses, logos, legends, etc. Network links give the ability to reference remote .kml or .kmz files, and refresh them periodically.

Loading the AGSKMLLayer also loads its underlying AGSKMLDataset, creating one if you didn't supply one through an initializer. The structure of a KML document can be examined through AGSKMLDataset::rootNodes after the AGSKMLDataset has successfully loaded. Missing or inaccessible .kml and .kmz files would cause loading to fail. Missing resources referenced by the KML document (such as images or files referenced via a network link will not prevent the layer from loading.

Performance characteristics KML files can vary significantly in the features they use, including 3D models, network links, and refresh intervals. Not all features are supported in 2D and 3D. For example, 3D models only appear when the KML layer is shown in a scene. Many KML files consist solely of a pointer to another KML file and a refresh interval. For example, the National Weather Service distributes forecast maps in the United States this way.

See also

AGSLayer, AGSKMLDataset, Sample: Display KML, Sample: Identify KML features, Sample: List KML contents, Sample: Create and Save KML File

License Restrictions:

This feature requires a Standard license for production deployment when using local .kml or .kmz file . No license required in Developer mode for testing.

Since

100.4

Inheritance diagram for AGSKMLLayer:

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

Class Methods
(instancetype)	+ KMLLayerWithItem:
(instancetype)	+ KMLLayerWithKMLDataset:

Properties
NSString *	attribution
BOOL	canChangeVisibility
AGSKMLDataset *	dataset
AGSEnvelope *	fullExtent
AGSTimeExtent *	fullTimeExtent
BOOL	identifyEnabled
AGSItem *	item
NSString *	layerDescription
NSString *	layerID
NSError *	loadError
AGSLoadStatus	loadStatus
double	maxScale
double	minScale
NSString *	name
float	opacity
BOOL	showInLegend
AGSSpatialReference *	spatialReference
NSArray< id< AGSLayerContent > > *	subLayerContents
void(^	subLayerContentsChangedHandler )(void)
BOOL	supportsTimeFiltering
BOOL	timeFilteringEnabled
AGSTimeValue *	timeInterval
AGSTimeValue *	timeOffset
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

initWithItem:

- (instancetype) initWithItem:

(AGSItem *)

item

Initialize this layer with an item representing a KML file or link to a KML resource. The item's type should be AGSPortalItemTypeKML.

Parameters

item	representing a KML file or link to a KML resource.

Returns

A new kml layer

Since

100.4

initWithKMLDataset:

- (instancetype) initWithKMLDataset:

(AGSKMLDataset *)

dataset

Initialize this layer with a KML dataset.

Parameters

dataset

The KML dataset.

Returns

A new kml layer

Since

100.4

isEqualToLayer:

- (BOOL) isEqualToLayer:

(AGSLayer *)

other

isVisibleAtScale:

- (BOOL) isVisibleAtScale:

(double)

scale

Check whether this layer is visible at a given scale.

Since

100

KMLLayerWithItem:

+ (instancetype) KMLLayerWithItem:

(AGSItem *)

item

Initialize this layer with an item representing a KML file or link to a KML resource. The item's type should be AGSPortalItemTypeKML.

Parameters

item	representing a KML file or link to a KML resource.

Returns

A new kml layer

Since

100.4

KMLLayerWithKMLDataset:

+ (instancetype) KMLLayerWithKMLDataset:

(AGSKMLDataset *)

dataset

Initialize this layer with a KML dataset.

Parameters

dataset

The KML dataset.

Returns

A new kml layer

Since

100.4

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

dataset

- (AGSKMLDataset*) dataset

readnonatomicstrong

The KML dataset used to create the layer.

Since

100.4

fullExtent

- (AGSEnvelope*) fullExtent

readnonatomicstronginherited

Full extent of the layer.

Since

100

fullTimeExtent

- (AGSTimeExtent*) fullTimeExtent

readnonatomicstronginherited

The full time extent of the layer 100.2

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

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

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

supportsTimeFiltering

- (BOOL) supportsTimeFiltering

readnonatomicassigninherited

Indicates whether the layer supports filtering its contents by a time range 100.2

timeFilteringEnabled

- (BOOL) timeFilteringEnabled

readwritenonatomicassigninherited

Indicates whether the layer must use the time extent defined on the owning AGSGeoView::timeExtent and filter its content. Only applicable if the layer supports time filtering (see supportsTimeFiltering) 100.2

timeInterval

- (AGSTimeValue*) timeInterval

readnonatomicstronginherited

Returns the suggested time slider step size for this time aware layer. Can be nil if no time interval is suggested for this time aware object.

100.2

timeOffset

- (AGSTimeValue*) timeOffset

readwritenonatomicstronginherited

A time offset for this layer. This is useful when data from different layers belong to different time periods and must be displayed together. The offset it applied on-the-fly, it does not change the actual data of the layer. The time offset is subtracted from the time extent set on the owning AGSGeoView::timeExtent before the extent is used to filter content from the layer. 100.2

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