MBVisualInstructionComponent.swift

#if os(OSX)
    import Cocoa
#elseif os(watchOS)
    import WatchKit
#else
    import UIKit
#endif

/**
 A component of a `VisualInstruction` that represents a single run of similarly formatted text or an image with a textual fallback representation.
 */
@objc(MBVisualInstructionComponent)
open class VisualInstructionComponent: NSObject, ComponentRepresentable {

    /**
    The URL to an image representation of this component.

    The URL refers to an image that uses the device’s native screen scale.
    */
    @objc public var imageURL: URL?

    /**
     An abbreviated representation of the `text` property.
     */
    @objc public var abbreviation: String?

    /**
     The priority for which the component should be abbreviated.

     A component with a lower abbreviation priority value should be abbreviated before a component with a higher abbreviation priority value.
     */
    @objc public var abbreviationPriority: Int = NSNotFound

    /**
     The plain text representation of this component.

     Use this property if `imageURL` is `nil` or if the URL contained in that property is not yet available.
     */
    @objc public var text: String?

    /**
     The type of visual instruction component. You can display the component differently depending on its type.
     */
    @objc public var type: VisualInstructionComponentType

    public static var supportsSecureCoding: Bool = true

    /**
     Initializes a new visual instruction component object based on the given JSON dictionary representation.

     - parameter json: A JSON object that conforms to the [banner component](https://docs.mapbox.com/api/navigation/#banner-instruction-object) format described in the Directions API documentation.
     */
    @objc(initWithJSON:)
    public convenience init(json: [String: Any]) {
        let text = json["text"] as? String
        let type = VisualInstructionComponentType(description: json["type"] as? String ?? "") ?? .text

        let abbreviation = json["abbr"] as? String
        let abbreviationPriority = json["abbr_priority"] as? Int ?? NSNotFound

        var imageURL: URL?
        if let baseURL = json["imageBaseURL"] as? String, !baseURL.isEmpty {
            let scale: CGFloat
            #if os(OSX)
                scale = NSScreen.main?.backingScaleFactor ?? 1
            #elseif os(watchOS)
                scale = WKInterfaceDevice.current().screenScale
            #else
                scale = UIScreen.main.scale
            #endif
            imageURL = URL(string: "\(baseURL)@\(Int(scale))x.png")
        }

        self.init(type: type, text: text, imageURL: imageURL, abbreviation: abbreviation, abbreviationPriority: abbreviationPriority)
    }

    /**
     Initializes a new visual instruction component object that displays the given information.

     - parameter type: The type of visual instruction component.
     - parameter text: The plain text representation of this component.
     - parameter imageURL: The URL to an image representation of this component.
     - parameter abbreviation: An abbreviated representation of `text`.
     - parameter abbreviationPriority: The priority for which the component should be abbreviated.
     */
    @objc public init(type: VisualInstructionComponentType, text: String?, imageURL: URL?, abbreviation: String?, abbreviationPriority: Int) {
        self.text = text
        self.type = type
        self.imageURL = imageURL
        self.abbreviation = abbreviation
        self.abbreviationPriority = abbreviationPriority
    }

    @objc public required init?(coder decoder: NSCoder) {
        self.text = decoder.decodeObject(of: NSString.self, forKey: "text") as String?

        guard let typeString = decoder.decodeObject(of: NSString.self, forKey: "type") as String?, let type = VisualInstructionComponentType(description: typeString) else {
            return nil
        }
        self.type = type


        guard let imageURL = decoder.decodeObject(of: NSURL.self, forKey: "imageURL") as URL? else {
            return nil
        }
        self.imageURL = imageURL

        guard let abbreviation = decoder.decodeObject(of: NSString.self, forKey: "abbreviation") as String? else {
            return nil
        }
        self.abbreviation = abbreviation

        abbreviationPriority = decoder.decodeInteger(forKey: "abbreviationPriority")
    }

    public func encode(with coder: NSCoder) {
        coder.encode(text, forKey: "text")
        coder.encode(type.description, forKey: "type")
        coder.encode(imageURL, forKey: "imageURL")
        coder.encode(abbreviation, forKey: "abbreviation")
        coder.encode(abbreviationPriority, forKey: "abbreviationPriority")
    }
}