AGSGeographicTransformation Class Reference

Description

Used to transform coordinates of geometries between spatial references that have two different geographic coordinate systems.

Each geographic transformation has an input and an output spatial reference. The transformation operates on the horizontal (geographic) datums in each spatial reference.

The inverse of the geographic transformation, if any, used to transform in the opposite direction, may be accessed using inverse (AGSDatumTransformation).

A geographic transformation can be constructed from a single geographic transformation step object, or from a list of geographic transformation steps objects that are chained together. Most transformations between spatial references that do not share the WGS 1984 datum use WGS 1984 as an intermediate datum. Thus, it is common to create a geographic transformation object with two geographic transformation steps: first to transform from the datum in the input spatial reference to WGS 1984, and then from WGS 1984 to the output spatial reference's datum. There are a limited number of transformations directly between two non-WGS84 datums, such as WKID 4461, which is NAD_1983_HARN_To_NAD_1983_NSRS2007_1. These do not need WGS 1984 as an intermediate datum.

In most cases, you do not need to construct your own AGSGeographicTransformation. You can get a list of suitable transformations for a given input and output spatial reference using one of the functions on the AGSTransformationCatalog.

A geographic transformation object is immutable.

See also

AGSTransformationCatalog to find a list of suitable tranformations between two spatial references

Since

100.2

Inheritance diagram for AGSGeographicTransformation:

Instance Methods
(instancetype)	- initWithStep:
(instancetype)	- initWithSteps:
(nullable AGSDatumTransformation *)	- inverse
(BOOL)	- isEqualToDatumTransformation:

Class Methods
(instancetype)	+ geographicTransformationWithStep:
(instancetype)	+ geographicTransformationWithSteps:

Properties
AGSSpatialReference *	inputSpatialReference
BOOL	missingProjectionEngineFiles
NSString *	name
AGSSpatialReference *	outputSpatialReference
NSArray< AGSGeographicTransformationStep * > *	steps

Method Documentation

geographicTransformationWithStep:

+ (instancetype) geographicTransformationWithStep:

(AGSGeographicTransformationStep *)

step

Initialize this transformation with a single step

Parameters

step	in the process of transforming between datums

Returns

Initialized geographic transformation

Since

100.2

geographicTransformationWithSteps:

+ (instancetype) geographicTransformationWithSteps:

(NSArray< AGSGeographicTransformationStep * > *)

steps

Initialize this transformation with multiple steps. Use this when the multi-step transformation is known in advance. The output of each step should match the input of the following step. Then, you can use the new multi-step transformation where you would use a single-step transformation.

Parameters

steps

An array containing AGSGeographicTransformationStep instances.

Returns

Initialized geographic transformation

Since

100.2

initWithStep:

- (instancetype) initWithStep:

(AGSGeographicTransformationStep *)

step

Initialize this transformation with a single step

Parameters

step	in the process of transforming between datums

Returns

Initialized geographic transformation

Since

100.2

initWithSteps:

- (instancetype) initWithSteps:

(NSArray< AGSGeographicTransformationStep * > *)

steps

Initialize this transformation with multiple steps. Use this when the multi-step transformation is known in advance. The output of each step should match the input of the following step. Then, you can use the new multi-step transformation where you would use a single-step transformation.

Parameters

steps

An array containing AGSGeographicTransformationStep instances.

Returns

Initialized geographic transformation

Since

100.2

inverse

- (nullable AGSDatumTransformation *) inverse

Returns the inverse of this datum transformation.

Since

100.2

isEqualToDatumTransformation:

- (BOOL) isEqualToDatumTransformation:

(AGSDatumTransformation *)

other

Compares this spatial reference with the provided one for equality.

Parameters

other

transformation to compare this one to.

Returns

boolean indicating whether the two transformation are equal

Since

100.2

Property Documentation

inputSpatialReference

- (AGSSpatialReference*) inputSpatialReference

readnonatomicstronginherited

The input spatial reference this transformation can be applied on.

Since

100.2

missingProjectionEngineFiles

- (BOOL) missingProjectionEngineFiles

readnonatomicassigninherited

Indicates whether any data files needed by the Projection Engine is missing from the local file system.

Note

In order for any Projection Engine files to be found, the location must be set upon application startup using setProjectionEngineDirectory:error: (AGSTransformationCatalog) before using any other Runtime API.

Since

100.2

name

- (NSString*) name

readnonatomiccopyinherited

The name of the datum transformation. For multi-step transformations, the name contains the concatenated names of each step's transformation, separated by a plus sign '+'. If the transformation is inverted, the name starts with a tilde (~).

Since

100.2

outputSpatialReference

- (AGSSpatialReference*) outputSpatialReference

readnonatomicstronginherited

The output spatial reference this transformation produces

Since

100.2

steps

- (NSArray<AGSGeographicTransformationStep*>*) steps

readnonatomiccopy

One or more steps used in the transformation.

Since

100.2