AGSLabelDefinition Class Reference

Description

An object that defines the text, appearance and position of labels for features for a given scale range.

An AGSLabelDefinition describes a class of labels. A collection of label definitions can be attached to a feature data source (e.g. AGSFeatureLayer). Each AGSLabelDefinition specifies:

• which features are covered by the definition, by applying the where-clause
• what text should be displayed, based on the individual feature's attributes and the label expression defined in the JSON.
• how the text should appear, using the label definition's AGSTextSymbol
• where the text should appear, with respect to its feature, using the AGSLabelDefinition::labelPlacement
• how to move or avoid other labels and features/graphics that would overlap each label

An instance of AGSLabelDefinition can be constructed from JSON as follows :

let labelDefinitionString = "{"
+ "  \"allowOverrun\": false,"
+ "  \"deconflictionStrategy\":\"static\","
+ "  \"labelExpressionInfo\": { \"expression\": \"round($feature.length,2) + 'm^2'\"},"
+ "  \"labelPlacement\": \"esriServerPolygonPlacementAlwaysHorizontal\","
+ "  \"lineConnection\": \"none\","
+ "  \"minScale\": 1999,"
+ "  \"maxScale\": 0,"
+ "  \"multiPart\": \"labelLargest\","
+ "  \"name\":\"Building interior code\","
+ "  \"priority\": 15,"
+ "  \"removeDuplicates\": \"featureType\","
+ "  \"removeDuplicatesDistance\": 300,"
+ "  \"repeatLabel\":false,"
+ "  \"repeatLabelDistance\":0,"
+ "  \"stackLabel\": true,"
+ "  \"stackAlignment\": \"dynamic\","
+ "  \"stackRowLength\": 20,"
+ "  \"stackBreakPosition\": \"before\","
+ "  \"symbol\": {\"type\": \"esriTS\", \"color\": [0,78,78,255], \"backgroundColor\": null, \"borderLineColor\": null, \"verticalAlignment\": \"bottom\", \"horizontalAlignment\": \"left\", \"rightToLeft\": false, \"angle\": 0, \"xoffset\": 0, \"yoffset\": 0, \"font\": {\"family\": \"Arial\", \"size\": 12, \"style\": \"normal\", \"weight\": \"bold\", \"decoration\": \"none\"}},"
+ "}"

if let jsonData = labelDefinitionString.data(using: .utf8) {
  do {
    //convert string data into JSON
   let JSON = try JSONSerialization.jsonObject(with: jsonData, options: JSONSerialization.ReadingOptions.mutableContainers)

    //convert JSON into AGSLabelDefinition
    let labelDefinition = try AGSLabelDefinition.fromJSON(JSON)
  }
  catch {
   print("Error: \(error.localizedDescription)")
  }
}

Since

100.1

See also

AGSFeatureLayer::labelsEnabled, AGSGraphicsOverlay::labelsEnabled, AGSArcGISMapImageSublayer::labelsEnabled to enable labels

AGSFeatureLayer::labelDefinitions, AGSGraphicsOverlay::labelDefinitions, AGSArcGISMapImageSublayer::labelDefinitions to specify label definitions

Inheritance diagram for AGSLabelDefinition:

Instance Methods
(nullable id)	- toJSON:

Class Methods
(nullable id< AGSJSONSerializable >)	+ fromJSON:error:

Properties
NSDictionary< NSString *, id > *	unknownJSON
NSDictionary< NSString *, id > *	unsupportedJSON

Method Documentation

fromJSON:error:()

+ (nullable id<AGSJSONSerializable>) fromJSON: (id)  JSONObject error: (NSError **)  error

staticrequiredinherited

Initializes and returns an object from its JSON representation.

Parameters

JSONObject	NSDictionary or NSArray containing the JSON.
error	encountered during the operation, if any.

Since

100

toJSON:()

- (nullable id) toJSON: (NSError **)  error

requiredinherited

Returns JSON representation for this object.

Parameters

error

encountered during the operation, if any.

Returns

NSDictionary or NSArray containing the JSON.

Since

100

Reimplemented in AGSPortalItem.

Property Documentation

unknownJSON

- (NSDictionary<NSString*,id>*) unknownJSON

readrequirednonatomiccopyinherited

A dictionary of values that was in the source JSON but was unparsed by API.

Returns

NSDictionary containing the unknown JSON.

Since

100

unsupportedJSON

- (NSDictionary<NSString*,id>*) unsupportedJSON

readnonatomiccopyinherited

A dictionary of values that are supported by the REST API, but not exposed through the SDK API.

Returns

NSDictionary containing the unsupported JSON.

Since

100