iOS Swift: Location Awareness, do task when location data is provided.

Awareness.swift

//
//  Awareness.swift
//  Edible
//
//  Created by Fuxing on 7/5/15.
//  Copyright (c) 2015 3Lines. All rights reserved.
//

import Foundation
import CoreLocation
import UIKit
import MapKit

class Awareness{
    static var location: CLLocation?
    
    class func distance(locationB: CLLocation) -> String?{
        if let location = location{
            let mdf = MKDistanceFormatter()
            mdf.units = .Metric
            return mdf.stringFromDistance(location.distanceFromLocation(locationB))
        }
        return nil
    }
    
    class func distanceInMeter(locationB: CLLocation) -> Double?{
        if let location = location{
            return location.distanceFromLocation(locationB)
        }
        return nil
    }
    
    // 5km per hour, 83m per minute, due to road complication, 120
    class func minuteWalkAway(locationB: CLLocation) -> String?{
        if let meter = distanceInMeter(locationB){
            let minute = Int(round(meter/120))
            if (minute == 0){
                return "< 0 mins walk"
            }else{
                return "\(minute) mins walk"
            }
        }
        return nil
    }
    
    class func update(newLocation: CLLocation){
        location = newLocation
        
        // Check queue and excute tasks
        while(taskQueue.count > 0){
            let latLng = getLatLng()
            taskQueue.removeLast()(lat: latLng.0, lng: latLng.1)
        }
    }
    
    class func getLatLng() -> (Double, Double){
        if let location = location{
            return (location.coordinate.latitude, location.coordinate.longitude)
        }
        return (0, 0)
    }
    
    // Get Awareness, can be empty if latLng are empty
    class func get() -> [String: AnyObject]{
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "HH:mm:ss"
        dateFormatter.timeZone = NSTimeZone()
        
//        let localDate = dateFormatter.stringFromDate(NSDate())
        if let location = location{
            return ["lat": location.coordinate.latitude, "lng": location.coordinate.longitude, "time": dateFormatter.stringFromDate(NSDate())]
        }
        return ["time": dateFormatter.stringFromDate(NSDate())]
    }
    
    // Type alias for queue task
    typealias QueueTask = (lat: Double, lng: Double) -> Void
    // Queue list
    static var taskQueue = [QueueTask]()
    
    // Run func when awareness is available
    class func runWhenAwarenessAvailable(task: QueueTask){
        if let _ = location{
            // Lat lng exist
            let latLng = getLatLng()
            task(lat: latLng.0, lng: latLng.1)
        }else{
            // Add task to queue
            taskQueue.append(task)
        }
    }
    
    class func runWhenAvailable(task: QueueTask){
        if let _ = location{
            // Lat lng exist
            let latLng = getLatLng()
            task(lat: latLng.0, lng: latLng.1)
        }else{
            // Add task to queue
            taskQueue.append(task)
        }
    }
}