Represents the spatial reference of a geometry.
A spatial reference determines how map coordinates, or the x,y,z-coordinates in the vertices of geometries, correspond to locations in real-world space. Therefore, it is very important to associate geometries representing spatial data with corresponding spatial references.
Each spatial reference can be represented by either a well-known ID (WKID), or a well-known text (WKT). Spatial references define the spatial properties of a geometry, for instance the coordinate system it uses. There are 2 broad classes of coordinate systems - Geographic & Projected. A Geographic Coordinate system uses a 3-dimensional spherical surface to define locations on the earth. A Projected Coordinate system on the other hand uses a flat, 2-dimensional surface.
Learn more about coordinate systems
AGSGeometry for geometry types
+ projectGeometry:toSpatialReference: (AGSGeometryEngine) to project geometries from one spatial reference to another
Calculate the grid convergence for a spatial reference at a given point.
Remarks
The grid convergence is the angle between True North and Grid North at a point on a map. The grid convergence can be used to convert a horizontal direction expressed as an azimuth in a geographic coordinate system (relative to True North) to a direction expressed as a bearing in a projected coordinate system (relative to Grid North), and vice versa.
Sign convention
The grid convergence returned by this method is positive when Grid North lies east of True North. The following formula demonstrates how to obtain a bearing (b) from an azimuth (a) using the grid convergence (c) returned by this method: b = a - c.
This sign convention is sometimes named the Gauss-Bomford convention.
Other Notes
0 if the spatial reference is a geographic coordinate systemNAN if the point is outside the projection's horizon or on errorInitializes and returns an object from its JSON representation.
NSDictionary or NSArray containing the JSON. error encountered during the operation, if any.
Creates a spatial reference with the given well-known ID (WKID).
Creates a spatial reference with the given well-known ID (WKID) and a vertical well-known ID.
Creates a spatial reference with the given well-known text (WKT).
Compares whether two spatial references are equal. They are equal if they have the same WKID or #WKT.
YES if the spatial references are equal.
Creates a spatial reference with the given well-known ID (WKID).
Creates a spatial reference with the given well-known ID (WKID) and a vertical well-known ID.
Creates a spatial reference with the given well-known text (WKT).
Returns JSON representation for this object.
NSDictionary or NSArray containing the JSON.
Reimplemented in AGSPortalItem.
◆ webMercatorA spatial reference representing the Web Mercator coordinate system (WKID:3857, equivalent to WKID:102113).
A spatial reference representing the WGS84 coordinate system (WKID:4326).
If the given spatial reference is a projected coordinate system, then this will return the geographic coordinate system of that system.
If the spatial reference is a projected coordinate system, then a spatial reference object representing the underlying geographic coordinate system is returned. Every projected coordinate system has an underlying geographic coordinate system. If the spatial reference is a geographic coordinate system, then a reference to itself is returned. If the spatial reference is a local spatial reference, a nil is returned.
YES if spatial reference is a Geographic Coordinate System.
YES if coordinate system is horizontally pannable.
YES if spatial reference is a Projected Coordinate System.
The unit of measure for the horizontal coordinate system of this spatial reference.
A dictionary of values that was in the source JSON but was unparsed by API.
NSDictionary containing the unknown JSON.
A dictionary of values that are supported by the REST API, but not exposed through the SDK API.
NSDictionary containing the unsupported JSON.
The well-known ID for the vertical coordinate system.
The well-known ID for the vertical coordinate system (VCS) set on this AGSSpatialReference.
Returns 0 if there is no VCS set, if there is a custom VCS set.
- initWithWKID:verticalWKID:
The well-known ID for the horizontal coordinate system.
The well-known ID for the horizontal coordinate system. Will return 0 if an error occurs.
The well-known text of the spatial reference.
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