AGSImageTiledLayer Class Reference

Description

A base class for layers that display cached maps. You would typically work with one or more sub-classes of this class.

AGSImageTiledLayer defines a base class for layers that display tiled map services and cached image services. This is an abstract class that can be derived in a custom class to implement a local tile data scheme. To implement a custom AGSImageTiledLayer, for example to load your own local tile data, you should derive from this type and supply the data for each tile as it is requested.

Additionally, implementers must also supply an AGSTileInfo that describes the tiling scheme, and an AGSEnvelope that defines the layer extent.

Implement this class if you want to create a custom tiled layer where the cached images cannot be referenced by a simple URL. If your images can be referenced by a simple URL, you should instead implement AGSServiceImageTiledLayer.

See also

AGSLayer, AGSServiceImageTiledLayer, AGSArcGISTiledLayer, AGSWMTSLayer, AGSWebTiledLayer, AGSOpenStreetMapLayer

Since

100

Inheritance diagram for AGSImageTiledLayer:

Instance Methods
(void)	- cancelLoad
(void)	- doCancelLoading
(void)	- doStartLoading:
(id< AGSCancelable >)	- fetchLegendInfosWithCompletion:
(instancetype)	- initWithTileInfo:fullExtent:
(BOOL)	- isEqualToLayer:
(BOOL)	- isVisibleAtScale:
(void)	- loadDidFinishWithError:
(void)	- loadWithCompletion:
(void)	- onLoadStatusChanged
(void)	- respondWithNoDataTileForTileKey:
(void)	- respondWithTileKey:data:error:
(void)	- retryLoadWithCompletion:

Class Methods
(instancetype)	+ imageTiledLayerWithTileInfo:fullExtent:

Properties
NSString *	attribution
float	brightness
void(^	cancelTileRequestHandler )(AGSTileKey *tileKey)
BOOL	canChangeVisibility
float	contrast
AGSEnvelope *	fullExtent
float	gamma
BOOL	identifyEnabled
AGSItem *	item
NSString *	layerDescription
NSString *	layerID
NSError *	loadError
AGSLoadStatus	loadStatus
double	maxScale
double	minScale
NSString *	name
AGSNoDataTileBehavior	noDataTileBehavior
float	opacity
BOOL	showInLegend
AGSSpatialReference *	spatialReference
NSArray< id< AGSLayerContent > > *	subLayerContents
void(^	subLayerContentsChangedHandler )(void)
AGSTileInfo *	tileInfo
void(^	tileRequestHandler )(AGSTileKey *tileKey)
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

imageTiledLayerWithTileInfo:fullExtent:

+ (instancetype) imageTiledLayerWithTileInfo:		(AGSTileInfo *)	tileInfo
fullExtent:		(AGSEnvelope *)	fullExtent

Creates a custom tiled layer with the provided details.

Parameters

tileInfo	specifying the tiling scheme used by the layer.
fullExtent	of the layer.

Returns

A new tiled layer.

Since

100

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

initWithTileInfo:fullExtent:

- (instancetype) initWithTileInfo:		(AGSTileInfo *)	tileInfo
fullExtent:		(AGSEnvelope *)	fullExtent

Creates a custom tiled layer with the provided details.

Parameters

tileInfo	specifying the tiling scheme used by the layer.
fullExtent	of the layer.

Since

100

Implemented in AGSServiceImageTiledLayer.

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

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).

respondWithNoDataTileForTileKey:

- (void) respondWithNoDataTileForTileKey:

(AGSTileKey *)

tileKey

Needs to be invoked when the custom layer does not find a tile.

Parameters

tileKey

specifying the tile that was requested.

Since

100

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

respondWithTileKey:data:error:

- (void) respondWithTileKey:		(AGSTileKey *)	tileKey
data:		(nullable NSData *)	data
error:		(nullable NSError *)	error

Needs to be invoked when the custom layer has successfully retrieved the tile requested in tileRequestHandler, or if an error is encountered while retrieving the tile.

Parameters

tileKey	specifying the tile that was requested.
data	for the retrieved tile if the operation was successful.
error	encountered while retrieving the tile if the operation failed.

Since

100

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

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

readwritenonatomiccopy

Attribution information of the layer.

Since

100

brightness

- (float) brightness

readwritenonatomicassigninherited

The brightness of the layer's map image. Default value is 0. Values in the range -100.0 to 100.0 are valid. Values outside that range are ignored.

Since

100

cancelTileRequestHandler

- (void(^ cancelTileRequestHandler) (AGSTileKey *tileKey))

readwritenonatomicstrong

The handler that will be invoked when a requested tile is no longer needed. This should be assigned a block that contains the business logic specific to the custom layer for canceling the requested tile.

Since

100

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

canChangeVisibility

- (BOOL) canChangeVisibility

readrequirednonatomicassigninherited

Denotes whether the layer can change visibility or not.

Since

100

contrast

- (float) contrast

readwritenonatomicassigninherited

The contrast of the layer's map image. Default value is 0. Values in the range -100.0 to 100.0 are valid. Values outside that range are ignored.

Since

100

fullExtent

- (AGSEnvelope*) fullExtent

readnonatomicstronginherited

Full extent of the layer.

Since

100

gamma

- (float) gamma

readwritenonatomicassigninherited

The gamma of the layer's map image. Default value is 0. Values in the range -100.0 to 100.0 are valid. Values outside that range are ignored.

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

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

noDataTileBehavior

- (AGSNoDataTileBehavior) noDataTileBehavior

readwritenonatomicassign

Determines how a tile request that returns 'NoData' is resampled.

Zooming in can result in tile requests with no tiles at the requested level of detail.

In this case, there are options that control what to display where the tile should be:

• AGSNoDataTileBehaviorUpSample - Resample the pixels from a lower level of detail tile. This can result in pixelation or blurriness. This is the default behavior for operational layers.

• AGSNoDataTileBehaviorBlank - The 'NoData' pixels will show the raster picture as being blank (or disappearing). This is the default behavior for basemap reference layers.

• AGSNoDataTileBehaviorShow - This will show the raster picture with the text 'No Data' stamped over it once you pass the lowest level-of-detail scale

Sometimes, to see the effect on the map when setting the AGSImageTiledLayer::noDataTileBehavior property, the AGSLayer::maxScale value must also be explicitly set. The AGSLayer::maxScale property may need to be smaller than the level-of-detail setting that was used to create the tiled images in ArcGIS Pro or ArcGIS Desktop. For example, consider an operational image tiled layer showing forest cover that was created with the level-of-detail assumption that it was to be viewed above a scale of 5000 (meaning you will not see 'NoData' until you zoom closer to the Earth than a 5000 scale). However, you want to be able to zoom in closer to the Earth surface, say down to 3000 or 300. By setting the AGSLayer::maxScale property to a number smaller than 5000, you will be able to zoom in closer to the Earth and see the effects of changing the AGSImageTiledLayer::noDataTileBehavior enumerations.

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

tileInfo

- (AGSTileInfo*) tileInfo

readnonatomicstrong

Tiling scheme for the layer.

Since

100

tileRequestHandler

- (void(^ tileRequestHandler) (AGSTileKey *tileKey))

readwritenonatomicstrong

The handler that will be invoked when a new tile is needed. This should be assigned a block that contains the business logic specific to the custom layer for fetching the requested tile. The block should eventually invoke respondWithTileKey:data:error: (AGSImageTiledLayer(CustomImageTiledLayer)) if a tile is retrieved or an error is encountered. Alternatively, it can invoke #respondWithNoDataTileForTileKey if no tile is available.

Since

100

Provided by category AGSImageTiledLayer(CustomImageTiledLayer).

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