[ios, macos] Insert example code in original headers (#7569)

* [ios, macos] Removed extraneous code fences

* [ios] Streamlined example delimiters

Use test method names as names of example blocks and test method documentation comments as front matter for examples. Set off example blocks using a syntax similar to playground markup syntax. Avoid hard-coding indentation levels. Trigger Xcode build error when an error occurs in the script.

* [ios] Removed platform-specific code from examples

* [ios] Fixed logic error

The comment said 200 while the code said 1,500.

* [ios] Formalize build phase input

* [ios] Insert examples into original source documentation

Rewrote the example code insertion script to work on the original source files and overwrite any existing code examples on the same symbols. The script uses SourceKitten to find the documentation comment for the symbol named by the test method.

Replaced the Run Script build phase that runs the example code insertion script with a make rule that runs the same script. Inlined skeleton examples minus the contents of the code blocks.

* [ios] Fixed syntax error

* [ios] Ran ios-add-examples-to-docs

* [ios] Avoid touching unchanged headers

* [ios] Refactored example insertion script

* [ios] Point jazzy at original sources

* [ios] Invoke SourceKitten only once

* [ios] Look for methods as well as properties

* [ios] Thoroughly search for code blocks in doc comments

Refactored the example code insertion script to index test methods by their names, then recursively search the SourceKitten output for documentation comments that contain Swift code blocks, replacing each code block with the associated test method body.

* [ios, macos] Enabled example insertion for macOS

The example code insertion script is now platform-agnostic.

* [ios, macos] Fixed documentation example tests

Set the map view’s style to a minimal local JSON file. Wait for the style to finish loading before running each test. Corrected CGVector type.

* [ios, macos] Dry run mode

The output of this mode isn’t a good indicator of whether any files would’ve needed to be changed, because the presence of a conditional compilation block in one of the test methods means this script would always change and revert the corresponding comment.

* [ios] Fixed test failure

The iOS implementation of MGLMapView tries to show the Streets style by default even if no access token has been set. Avoid a race condition and frequent test failure by specifying the minimal style on initialization.

* [ios, macos] Ensure SourceKitten is installed before inserting example code

* [ios, macos] Tear down map view after each test

Keep map views from previous tests from hanging around, potentially obscuring the result of a subsequent test. Set the access token to a bogus token upfront for all style layer tests. Unified MGLStyle usage within MGLStyleTests.

* [ios, macos] Reinsert examples after generating runtime styling headers

1 files changed, 16 insertions, 0 deletions

diff --git a/platform/ios/DEVELOPING.md b/platform/ios/DEVELOPING.md
index 94ff49ee1b..f7bc0cc415 100644
--- a/platform/ios/DEVELOPING.md
+++ b/platform/ios/DEVELOPING.md
@@ -118,6 +118,22 @@ To add a localization to the iOS SDK:
 1. In the Project navigator, expand each .strings and .stringsdict file in the project. An additional version for your localization should be listed; translate it. Translate everything on the right side of the equals sign. Leave the left side and any comments unmodified. See Apple’s documentation on the [.strings](https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/LoadingResources/Strings/Strings.html) and [.stringsdict](https://developer.apple.com/library/content/documentation/MacOSX/Conceptual/BPInternational/StringsdictFileFormat/StringsdictFileFormat.html) formats.
 1. You’re already most of the way towards localizing the macOS SDK too – consider [completing that localization](../macos/DEVELOPING.md#adding-a-localization).
 
+### Adding a code example
+
+To add an example code listing to the documentation for a class or class member:
+
+1. Add a test method named in the form `testMGLClass` or `testMGLClass$method`
+   to [MGLDocumentationExampleTests](test/MGLDocumentationExampleTests.swift).
+   Wrap the code you’d like to appear in the documentation within
+   `//#-example-code` and `//#-end-example-code` comments.
+1. Insert the code listings into the headers:
+
+```bash
+make darwin-update-examples
+```
+
+[SourceKitten](https://github.com/jpsim/SourceKitten/) is required and will be installed automatically using Homebrew.
+
 ## Testing
 
 `make ios-test` builds and runs unit tests of cross-platform code as well as the SDK.