ArcGIS Runtime SDK for iOS: AGSLoadableBase Class Reference
ArcGIS Runtime SDK for iOS  100.6
AGSLoadableBase Class Reference

Description

A base class for objects that can load data asynchronously, for example, from a remote network location or the local file system.

It provides some basic plumbing that make it easier to adopt the <AGSLoadable> protocol. For example, you don't have to worry about keeping references to completion blocks, loading data on background threads, invoking completion blocks, managing the load status, and so on; this base class will handle all that.

Subclasses need only pay attention to the methods defined in AGSLoadableBase(ForSubclassEyesOnly)

See also
AGSLoadableBase(ForSubclassEyesOnly) for implementing loadables
Since
100
Inheritance diagram for AGSLoadableBase:
AGSObject <AGSLoadable> AGSArcGISSublayer AGSBasemap AGSElevationSource AGSENCCell AGSENCExchangeSet AGSFeatureCollection AGSFeatureTable AGSGeodatabase AGSGeoPackage AGSItemResourceCache AGSKMLDataset AGSLayer AGSLoadableImage AGSLoadableRemoteResourceBase AGSLoadableValue AGSMap AGSMobileMapPackage AGSMobileScenePackage AGSOfflineMapSyncTask AGSOfflineMapTask AGSPopupAttachment AGSPortal AGSPortalUser AGSPreplannedMapArea AGSRaster AGSScene AGSSurface AGSTileCache AGSUtilityNetwork AGSVectorTileCache AGSWMSService AGSWMTSService

Instance Methods

(void) - cancelLoad
 
(void) - loadWithCompletion:
 
(void) - retryLoadWithCompletion:
 

Properties

NSError * loadError
 
AGSLoadStatus loadStatus
 

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

§ 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
completionblock 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

§ 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
completionblock 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

§ 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