[ios, macos] Rename Data-driven styling guide (#8627)

* [ios, macos] Rename Data-driven styling guide

This turns the Data-driven styling guide into a guide for working with
style functions. This helps clarify that not all style functions are
DDS specific but keeps the discussion of this related functionality in
the same guide.

2 files changed, 11 insertions, 10 deletions

diff --git a/platform/darwin/docs/guides/For Style Authors.md.ejs b/platform/darwin/docs/guides/For Style Authors.md.ejs
index 93ca7014a3..86f8c46f53 100644
--- a/platform/darwin/docs/guides/For Style Authors.md.ejs
+++ b/platform/darwin/docs/guides/For Style Authors.md.ejs
@@ -308,8 +308,7 @@ iOS.
 
 A _style function_ allows you to vary the value of a layout or paint attribute
 based on the zoom level, data provided by content sources, or both. For more
-information about style functions that incorporate data from sources, see
-“[Data-Driven Styling](data-driven-styling.html)”.
+information about style functions, see “[Using Style Functions at Runtime](using-style-functions-at-runtime.html)”.
 
 Each kind of style function is represented by a distinct class, but you
 typically create style functions as you create any other style value, using
diff --git a/platform/darwin/docs/guides/Data-Driven Styling.md.ejs b/platform/darwin/docs/guides/Using Style Functions at Runtime.md.ejs
index 7b597c6737..bd477042c7 100644
--- a/platform/darwin/docs/guides/Data-Driven Styling.md.ejs
+++ b/platform/darwin/docs/guides/Using Style Functions at Runtime.md.ejs
@@ -10,19 +10,21 @@
   Edit platform/darwin/scripts/generate-style-code.js, then run `make darwin-style-code`.
 -->
 
-# Data-Driven Styling
+# Using Style Functions at Runtime
 
-Mapbox’s data-driven styling features allow you to use attributes in the data to style your maps. You can style map features automatically based on their individual attributes.
+[Runtime Styling](runtime-styling.html) enables you to modify every aspect of the map’s appearance dynamically as a user interacts with your application. Much of the runtime styling API allows you to specify _style functions_ instead of constant values. A style function allows you to specify in advance how a layout or paint attribute will vary as the zoom level changes or how the appearance of individual features vary based on metadata provided by a content source.
 
-Vary POI icons, transit route line colors, city polygon opacity, and more based on any attribute in your data. Need to visualize hotel data by price? You can have your map’s point radii and colors change automatically with your data.
+Style functions spare you the inconvenience of manually calculating intermediate values between different zoom levels or creating a multitude of style layers to handle homogeneous features in the map content. For example, if your content source indicates the prices of hotels in an area, you can color-code the hotels by price, relying on a style function to smoothly interpolate among desired colors without having to specify the color for each exact price.
 
-![available bikes](img/data-driven-styling/citibikes.png) ![subway lines](img/data-driven-styling/polylineExample.png)
+_Data-driven styling_ specifically refers to the use of style functions to vary the map’s appearance based on data in a content source.
+
+You can also specify style functions in a style JSON file, to be applied automatically when the map loads. See the [Mapbox Style Specification](https://www.mapbox.com/mapbox-gl-js/style-spec/#types-function) for details.
 
-This guide uses earthquake data from the [U.S. Geological Survey](https://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php) to style a map based on attributes. For more information about how to work with GeoJSON data in our iOS SDK, please see our [working with GeoJSON data](working-with-geojson-data.html) guide.
+![available bikes](img/data-driven-styling/citibikes.png) ![subway lines](img/data-driven-styling/polylineExample.png)
 
-## Style functions
+This guide uses earthquake data from the [U.S. Geological Survey](https://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php) and data-driven styling to style a map based on attributes. For more information about how to work with GeoJSON data in our iOS SDK, please see our [working with GeoJSON data](working-with-geojson-data.html) guide.
 
-There are three subclasses of `MGLStyleFunction`:
+A style function is represented at runtime by the `MGLStyleFunction` class. There are three subclasses of `MGLStyleFunction`:
 
 * `MGLCameraStyleFunction` is a style value that changes with zoom level. For example, you can make the radius of a circle increase according to zoom level.
 * `MGLSourceStyleFunction` is a style value that changes with the attributes of a feature. For example, you can adjust the radius of a circle based on the magnitude of an earthquake.
@@ -123,7 +125,7 @@ layer.circleColor = MGLStyleValue(interpolationMode: .interval,
 
 At each stop, `MGLInterpolationModeCategorical` produces an output value equal to the function input. We’re going to use a different stops dictionary than we did for the previous two modes.
 
-There are three main types of events in the dataset: earthquakes, explosions, and quarry blasts. In this case, the color of the circle layer will be determined by the type of event, with a default value of green to catch any events that do not fall into any of those categories.
+There are three main types of events in the dataset: earthquakes, explosions, and quarry blasts. In this case, the color of the circle layer will be determined by the type of event, with a default value of blue to catch any events that do not fall into any of those categories.
 
 ``` swift
 let categoricalStops = ["earthquake": MGLStyleValue<<%- cocoaPrefix %>Color>(rawValue: .orange),