Runtime styling API for iOS/macOS (#5727)

* [ios] wip runtime styling

* [ios, macos] Outlined header templates

* [ios, macos] cleanup and use appropiate data types

* [ios, macos] removed refs to mbgl and added convenient color methods on UIColor and NSColor

* [ios, macos] updated header template, included doc string

* [ios, macos] outlined template for layer implementation files

* [ios, macos] moved script to platform/darwin and updated comments

* [ios, macos] Cleaned up the implementation template

* [ios, macos] removed unused function and added support for more datatypes

* [ios, macos] overhauling the type protocols

* [ios, macos] removed unnecessary style classes

* [ios, macos] added support for more types

* [ios, macos] fixed string and number prop values

* [ios, macos] enum getters

* [ios, macos] added removeLayer() and removed unused layer ref

* [ios, macos] fixed remaining layer types and converted style layer into a protocol

* [ios, macos] fixed addLayer() and added example for line layer

* [ios] GeoJSON source now works

* [ios] fixed raster layer and raster source

* [ios] fixed attr prop number and outlined prop function

* [ios] wip functions

* [ios] bool and float function fix

* [ios] cleanup

* [macos] fixed support for macos

* [ios] fixed string functions

* [ios] extended array functions

* [ios] added tests and fixed a few bugs

* [ios] less verbose functions and improved tests

* [ios, macos] Removed unnecessary use of default arguments

Default arguments aren’t supported in Node v4, and they aren’t needed here anyways, because we’re only testing for truthiness.

* [ios, macos] Enum setters

Rely on a macro instead of category methods to specialize the setter implementation for enum attributes, since generic types are disallowed in Objective-C method signatures and mbgl::style::PropertyType must be type-qualified.

* [ios, macos] Got macOS closer to parity w/ iOS

Added various classes and test classes to the macOS workspace. Also fixed lots of compiler errors and updated macosapp runtime styling example to use the new dictionary syntax for function stops.

Updated all conversions from Objective-C stops to C++ stops to enumerate over the dictionary. Fixed compiler errors in enum setter implementations.

Also corrected path to script in generated file comments.

* [ios, macos] Added EJS templates to project

* [ios, macos] Code formatting

Made code format more consistent.

* [ios, macos] Spelled out ID

Cocoa convention is to always spell out “ID” as “identifier”, in part to avoid confusion with the id keyword. Also, URL is capitalized in most contexts, including property names.

* [ios, macos] Grouped related headers together

* [ios, macos] Cleaned up layer transformation

Also added support for converting background layers into Objective-C.

* [ios, macos] Cleaned up tests

Also made the tests work on macOS by introducing a new window to host the map.

* [ios, macos] Replaced TODOs with #warnings

* [ios] convert array based property values

* [ios, macos] color function/undefined getter

* [ios, macos] fixed function/undefined getters for bool and float properties

* [ios, macos] more function/undefined property getters

* [ios, macos] more type conversion and cleanup

* [ios, macos] disable macos runtime styling tests for now

* [ios, macos] cleaned up style code script

* [ios, macos] more type conversion

* [ios] added a base layer to handle visibility min/max zoom

* [macos] fixed base layer

* [ios, macos] use accessor methods

* [ios, macos] cleanup

* [ios, macos] add geojson to ios and macos

* [macos] rebase fix

* [ios, macos] fixed enum getters and added tests for enums

* [ios, macos] added an update method to base layer

* [ios, macos] added some documentation

* [ios, macos] docs

* [ios, macos] removed refs to filters for now

* [ios, macos] various tail work

* [ios, macos] missing import and incorrect type

1 files changed, 54 insertions, 1 deletions

diff --git a/platform/darwin/src/MGLStyle.h b/platform/darwin/src/MGLStyle.h
index 8577522b96..368557fc81 100644
--- a/platform/darwin/src/MGLStyle.h
+++ b/platform/darwin/src/MGLStyle.h
@@ -2,6 +2,10 @@
 
 #import "MGLTypes.h"
 
+#import "MGLStyleLayer.h"
+
+@class MGLSource;
+
 NS_ASSUME_NONNULL_BEGIN
 
 /**
@@ -32,6 +36,8 @@ static const NSInteger MGLStyleDefaultVersion = 9;
  */
 @interface MGLStyle : NSObject
 
+#pragma mark Default Style URLs
+
 /**
  Returns the URL to version 8 of the
  <a href="https://www.mapbox.com/maps/streets/">Mapbox Streets</a> style.
@@ -158,7 +164,54 @@ static const NSInteger MGLStyleDefaultVersion = 9;
  */
 + (NSURL *)satelliteStreetsStyleURLWithVersion:(NSInteger)version;
 
-- (instancetype)init NS_UNAVAILABLE;
+#pragma mark Runtime Styling
+
+/**
+ Returns a layer that conforms to `MGLStyleLayer` if any layer with the given
+ identifier was found.
+ 
+ @return layer A layer instance of the corresponding type.
+ */
+- (nullable id <MGLStyleLayer>)layerWithIdentifier:(NSString *)identifier;
+
+/**
+ Adds a new layer at the top of the hierarchy.
+ 
+ @param styleLayer The layer object to add to the map view. This object
+ must conform to the `MGLStyleLayer` protocol.
+ */
+- (void)addLayer:(id <MGLStyleLayer>)styleLayer;
+
+/**
+ Inserts a new layer below another layer.
+ 
+ @param styleLayer Layer to be inserted.
+ @param belowLayer A layer that's already on the map view.
+ */
+- (void)insertLayer:(id <MGLStyleLayer>)styleLayer
+         belowLayer:(id <MGLStyleLayer>)belowLayer;
+
+/**
+ Removes a layer from the map view.
+ 
+ @param styleLayer The layer object to remove from the map view. This object
+ must conform to the `MGLStyleLayer` protocol.
+ */
+- (void)removeLayer:(id <MGLStyleLayer>)styleLayer;
+
+/**
+ Adds a new source to the map view.
+ 
+ @param source The source to add to the map view.
+ */
+- (void)addSource:(MGLSource *)source;
+
+/**
+ Removes a source from the map view.
+ 
+ @param source The source to remove.
+ */
+- (void)removeSource:(MGLSource *)source;
 
 @end