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diff --git a/platform/ios/docs/guides/For Style Authors.md b/platform/ios/docs/guides/For Style Authors.md new file mode 100644 index 0000000000..753eb7200c --- /dev/null +++ b/platform/ios/docs/guides/For Style Authors.md @@ -0,0 +1,306 @@ +<!-- + This file is generated. + Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`. +--> +# Information for Style Authors + +A _style_ defines a map view’s content and appearance. If you’ve authored a +style using +[Mapbox Studio’s Styles editor](https://www.mapbox.com/studio/styles/) or as +JSON in a text editor, you can use that style in this SDK and manipulate it +afterwards in code. This document provides information you can use to ensure a +seamless transition from Mapbox Studio to your application. + +## Designing for iOS + +When designing your style, consider the context in which your application shows +the style. There are a number of considerations specific to iOS that may +not be obvious when designing your style in Mapbox Studio on the Web. A map view +is essentially a graphical user interface element, so many of same issues in +user interface design also apply when designing a map style. + +### Color + +Ensure sufficient contrast in your application’s user interface when your map +style is present. Standard user interface elements such as toolbars, sidebars, +and sheets often overlap the map view with a translucent, blurred background, so +make sure the contents of these elements remain legible with the map view +underneath. +The user location annotation view, the attribution button, any buttons in +callout views, and any items in the navigation bar are influenced by your +application’s tint color, so choose a tint color that constrasts well with your +map style. If you intend your style to be used in the dark, consider the impact +that Night Shift may have on your style’s colors. + +### Typography and graphics + +Choose font and icon sizes appropriate to iOS devices. iPhones and iPads have +smaller screens than the typical browser window in which you would use Mapbox +Studio, especially when multitasking is enabled. Your user’s viewing distance +may be shorter than on a desktop computer. Some of your users may use the Larger +Dynamic Type and Accessibility Text features to increase the size of all text on +the device. You can use the +[runtime styling API](#manipulating-the-style-at-runtime) to adjust your style’s +font and icon sizes accordingly. + +Design sprite images and choose font weights that look crisp on both +standard-resolution displays and Retina displays. This SDK supports the same +resolutions as iOS. +Standard-resolution displays are limited to older devices that your application +may or may not support, depending on its minimum deployment target. + +Icon and text labels should be legible regardless of the map’s orientation. +By default, this SDK makes it easy for your users to rotate or tilt the map +using multitouch gestures. +If you do not intend your design to accommodate rotation and tilting, disable +these gestures using the `MGLMapView.rotateEnabled` and +`MGLMapView.pitchEnabled` properties, respectively, or the corresponding +inspectables in Interface Builder. + +### Interactivity + +Pay attention to whether elements of your style appear to be interactive. +A text label may look like a tappable button merely due to matching your +application’s tint color or the default blue tint color. +You can make an icon or text label interactive by installing a gesture +recognizer and performing feature querying (e.g., +`-[MGLMapView visibleFeaturesAtPoint:]`) to get details about the selected +feature. + +Make sure your users can easily distinguish any interactive elements from the +surrounding map, such as pins, the user location annotation view, or a route +line. Avoid relying on hover effects to indicate interactive elements. Leave +enough room between interactive elements to accommodate imprecise tapping +gestures. + +For more information about user interface design, consult Apple’s +[_iOS Human Interface Guidelines_](https://developer.apple.com/ios/human-interface-guidelines/). + +## Applying your style + +You set an `MGLMapView` object’s style either in code, by setting the +`MGLMapView.styleURL` property, or in Interface Builder, by setting the “Style +URL” inspectable. The URL must point to a local or remote style JSON file. The +style JSON file format is defined by the +[Mapbox Style Specification](https://www.mapbox.com/mapbox-gl-style-spec/). This +SDK supports the functionality defined by version 8 of the specification unless +otherwise noted in the +[style specification documentation](https://www.mapbox.com/mapbox-gl-style-spec/). + +## Manipulating the style at runtime + +The _runtime styling API_ enables you to modify every aspect of a style +dynamically as a user interacts with your application. The style itself is +represented at runtime by an `MGLStyle` object, which provides access to various +`MGLSource` and `MGLStyleLayer` objects that represent content sources and style +layers, respectively. +For more information about the capabilities exposed by the runtime styling API, +see “[Runtime Styling](runtime-styling.html)”. + +The names of runtime styling classes and properties on iOS are generally +consistent with the style specification and Mapbox Studio’s Styles editor. Any +exceptions are listed in this document. + +To avoid conflicts with Objective-C keywords or Cocoa terminology, this SDK uses +the following terms for concepts defined in the style specification: + +In the style specification | In the SDK +---------------------------|--------- +class | style class +filter | predicate +id | identifier +image | style image +layer | style layer +property | attribute +SDF icon | template image +source | content source + +## Specifying the map’s content + +Each source defined by a style JSON file is represented at runtime by a content +source object that you can use to initialize new style layers. The content +source object is a member of one of the following subclasses of `MGLSource`: + +In style JSON | In the SDK +--------------|----------- +`geojson` | `MGLShapeSource` +`raster` | `MGLRasterSource` +`vector` | `MGLVectorSource` + +`image` and `video` sources are not supported. + +### Tile sources + +Raster and vector sources may be defined in TileJSON configuration files. This +SDK supports the properties defined in the style specification, which are a +subset of the keys defined in version 2.1.0 of the +[TileJSON](https://github.com/mapbox/tilejson-spec/tree/master/2.1.0) +specification. As an alternative to authoring a custom TileJSON file, you may +supply various tile source options when creating a raster or vector source. +These options are detailed in the `MGLTileSourceOption` documentation: + +In style JSON | In TileJSON | In the SDK +--------------|---------------|----------- +`url` | — | `configurationURL` parameter in `-[MGLTileSource initWithIdentifier:configurationURL:]` +`tiles` | `tiles` | `tileURLTemplates` parameter in `-[MGLTileSource initWithIdentifier:tileURLTemplates:options:]` +`minzoom` | `minzoom` | `MGLTileSourceOptionMinimumZoomLevel` +`maxzoom` | `maxzoom` | `MGLTileSourceOptionMaximumZoomLevel` +`tileSize` | — | `MGLTileSourceOptionTileSize` +`attribution` | `attribution` | `MGLTileSourceOptionAttributionHTMLString` (but consider specifying `MGLTileSourceOptionAttributionInfos` instead for improved security) +`scheme` | `scheme` | `MGLTileSourceOptionTileCoordinateSystem` + +### Shape sources + +Shape sources also accept various options. These options are detailed in the +`MGLShapeSourceOption` documentation: + +In style JSON | In the SDK +-----------------|----------- +`data` | `url` parameter in `-[MGLShapeSource initWithIdentifier:URL:options:]` +`maxzoom` | `MGLShapeSourceOptionMaximumZoomLevel` +`buffer` | `MGLShapeSourceOptionBuffer` +`tolerance` | `MGLShapeSourceOptionSimplificationTolerance` +`cluster` | `MGLShapeSourceOptionClustered` +`clusterRadius` | `MGLShapeSourceOptionClusterRadius` +`clusterMaxZoom` | `MGLShapeSourceOptionMaximumZoomLevelForClustering` + +To create a shape source from local GeoJSON data, first +[convert the GeoJSON data into a shape](working-with-geojson-data.html#converting-geojson-data-into-shape-objects), +then use the `-[MGLShapeSource initWithIdentifier:shape:options:]` method. + +## Configuring the map content’s appearance + +Each layer defined by the style JSON file is represented at runtime by a style +layer object, which you can use to refine the map’s appearance. The style layer +object is a member of one of the following subclasses of `MGLStyleLayer`: + +In style JSON | In the SDK +--------------|----------- +`background` | `MGLBackgroundStyleLayer` +`circle` | `MGLCircleStyleLayer` +`fill` | `MGLFillStyleLayer` +`line` | `MGLLineStyleLayer` +`raster` | `MGLRasterStyleLayer` +`symbol` | `MGLSymbolStyleLayer` + +You configure layout and paint attributes by setting properties on these style +layer objects. The property names generally correspond to the style JSON +properties, except for the use of camelCase instead of kebab-case. Properties +whose names differ from the style specification are listed below: + +### Circle style layers + +In style JSON | In Objective-C | In Swift +--------------|----------------|--------- +`circle-pitch-scale` | `MGLCircleStyleLayer.circleScaleAlignment` | `MGLCircleStyleLayer.circleScaleAlignment` +`circle-translate` | `MGLCircleStyleLayer.circleTranslation` | `MGLCircleStyleLayer.circleTranslation` +`circle-translate-anchor` | `MGLCircleStyleLayer.circleTranslationAnchor` | `MGLCircleStyleLayer.circleTranslationAnchor` + +### Fill style layers + +In style JSON | In Objective-C | In Swift +--------------|----------------|--------- +`fill-antialias` | `MGLFillStyleLayer.fillAntialiased` | `MGLFillStyleLayer.isFillAntialiased` +`fill-translate` | `MGLFillStyleLayer.fillTranslation` | `MGLFillStyleLayer.fillTranslation` +`fill-translate-anchor` | `MGLFillStyleLayer.fillTranslationAnchor` | `MGLFillStyleLayer.fillTranslationAnchor` + +### Line style layers + +In style JSON | In Objective-C | In Swift +--------------|----------------|--------- +`line-dasharray` | `MGLLineStyleLayer.lineDashPattern` | `MGLLineStyleLayer.lineDashPattern` +`line-translate` | `MGLLineStyleLayer.lineTranslation` | `MGLLineStyleLayer.lineTranslation` +`line-translate-anchor` | `MGLLineStyleLayer.lineTranslationAnchor` | `MGLLineStyleLayer.lineTranslationAnchor` + +### Raster style layers + +In style JSON | In Objective-C | In Swift +--------------|----------------|--------- +`raster-brightness-max` | `MGLRasterStyleLayer.maximumRasterBrightness` | `MGLRasterStyleLayer.maximumRasterBrightness` +`raster-brightness-min` | `MGLRasterStyleLayer.minimumRasterBrightness` | `MGLRasterStyleLayer.minimumRasterBrightness` +`raster-hue-rotate` | `MGLRasterStyleLayer.rasterHueRotation` | `MGLRasterStyleLayer.rasterHueRotation` + +### Symbol style layers + +In style JSON | In Objective-C | In Swift +--------------|----------------|--------- +`icon-allow-overlap` | `MGLSymbolStyleLayer.iconAllowsOverlap` | `MGLSymbolStyleLayer.iconAllowsOverlap` +`icon-ignore-placement` | `MGLSymbolStyleLayer.iconIgnoresPlacement` | `MGLSymbolStyleLayer.iconIgnoresPlacement` +`icon-image` | `MGLSymbolStyleLayer.iconImageName` | `MGLSymbolStyleLayer.iconImageName` +`icon-optional` | `MGLSymbolStyleLayer.iconOptional` | `MGLSymbolStyleLayer.isIconOptional` +`icon-rotate` | `MGLSymbolStyleLayer.iconRotation` | `MGLSymbolStyleLayer.iconRotation` +`icon-size` | `MGLSymbolStyleLayer.iconScale` | `MGLSymbolStyleLayer.iconScale` +`icon-keep-upright` | `MGLSymbolStyleLayer.keepsIconUpright` | `MGLSymbolStyleLayer.keepsIconUpright` +`text-keep-upright` | `MGLSymbolStyleLayer.keepsTextUpright` | `MGLSymbolStyleLayer.keepsTextUpright` +`text-max-angle` | `MGLSymbolStyleLayer.maximumTextAngle` | `MGLSymbolStyleLayer.maximumTextAngle` +`text-max-width` | `MGLSymbolStyleLayer.maximumTextWidth` | `MGLSymbolStyleLayer.maximumTextWidth` +`symbol-avoid-edges` | `MGLSymbolStyleLayer.symbolAvoidsEdges` | `MGLSymbolStyleLayer.symbolAvoidsEdges` +`text-field` | `MGLSymbolStyleLayer.text` | `MGLSymbolStyleLayer.text` +`text-allow-overlap` | `MGLSymbolStyleLayer.textAllowsOverlap` | `MGLSymbolStyleLayer.textAllowsOverlap` +`text-font` | `MGLSymbolStyleLayer.textFontNames` | `MGLSymbolStyleLayer.textFontNames` +`text-size` | `MGLSymbolStyleLayer.textFontSize` | `MGLSymbolStyleLayer.textFontSize` +`text-ignore-placement` | `MGLSymbolStyleLayer.textIgnoresPlacement` | `MGLSymbolStyleLayer.textIgnoresPlacement` +`text-justify` | `MGLSymbolStyleLayer.textJustification` | `MGLSymbolStyleLayer.textJustification` +`text-optional` | `MGLSymbolStyleLayer.textOptional` | `MGLSymbolStyleLayer.isTextOptional` +`text-rotate` | `MGLSymbolStyleLayer.textRotation` | `MGLSymbolStyleLayer.textRotation` +`icon-translate` | `MGLSymbolStyleLayer.iconTranslation` | `MGLSymbolStyleLayer.iconTranslation` +`icon-translate-anchor` | `MGLSymbolStyleLayer.iconTranslationAnchor` | `MGLSymbolStyleLayer.iconTranslationAnchor` +`text-translate` | `MGLSymbolStyleLayer.textTranslation` | `MGLSymbolStyleLayer.textTranslation` +`text-translate-anchor` | `MGLSymbolStyleLayer.textTranslationAnchor` | `MGLSymbolStyleLayer.textTranslationAnchor` + +## Setting attribute values + +Each property representing a layout or paint attribute is set to an +`MGLStyleValue` object, which is either an `MGLStyleConstantValue` object (for +constant values) or an `MGLStyleFunction` object (for zoom level functions). The +style value object is a container for the raw value or function parameters that +you want the attribute to be set to. + +In contrast to the JSON type that the style specification defines for each +layout or paint property, the style value object often contains a more specific +Foundation or Cocoa type. General rules for attribute types are listed below. +Pay close attention to the SDK documentation for the attribute you want to get +or set. + +In style JSON | In Objective-C | In Swift +--------------|-----------------------|--------- +Color | `UIColor` | `UIColor` +Enum | `NSValue` (see `NSValue(MGLAdditions)`) | `NSValue` (see `NSValue(MGLAdditions)`) +String | `NSString` | `String` +Boolean | `NSNumber.boolValue` | `Bool` +Number | `NSNumber.floatValue` | `Float` +Array (`-dasharray`) | `NSArray<NSNumber>` | `[Float]` +Array (`-font`) | `NSArray<NSString>` | `[String]` +Array (`-offset`, `-translate`) | `NSValue.CGVectorValue` | `NSValue.cgVectorValue` +Array (`-padding`) | `NSValue.UIEdgeInsetsValue` | `NSValue.uiEdgeInsetsValue` + +For padding attributes, note that the arguments to +`UIEdgeInsetsMake()` in Objective-C and +`EdgeInsets(top:left:bottom:right:)` in Swift are specified in counterclockwise +order, in contrast to the clockwise order defined by the style specification. + +## Filtering sources + +You can filter a shape or vector source by setting the +`MGLVectorStyleLayer.predicate` property to an `NSPredicate` object. Below is a +table of style JSON operators and the corresponding operators used in the +predicate format string: + +In style JSON | In the format string +--------------------------|--------------------- +`["has", key]` | `key != nil` +`["!has", key]` | `key == nil` +`["==", key, value]` | `key == value` +`["!=", key, value]` | `key != value` +`[">", key, value]` | `key > value` +`[">=", key, value]` | `key >= value` +`["<", key, value]` | `key < value` +`["<=", key, value]` | `key <= value` +`["in", key, v0, …, vn]` | `key IN {v0, …, vn}` +`["!in", key, v0, …, vn]` | `NOT key IN {v0, …, vn}` +`["all", f0, …, fn]` | `p0 AND … AND pn` +`["any", f0, …, fn]` | `p0 OR … OR pn` +`["none", f0, …, fn]` | `NOT (p0 OR … OR pn)` + +See the `MGLVectorStyleLayer.predicate` documentation for a full description of +the supported operators and operand types. |