iOS Swift3 - Convert coordinate - ios

Question

I'm trying to create annotations on the MapKit from a geoJSON file, but the problem is that the coordinates provided by the geoJSON file don't match the coordinate system that MapKit uses.
Question : How do I convert read the geoJSON file and convert the coordinates from `` to WGS84S?
Here is an example of what the geoJSON file looks like:
{"name":"MAPADDRESSPOINT","type":"FeatureCollection"
,"crs":{"type":"name","properties":{"name":"EPSG:3008"}}
,"features":[
{"type":"Feature","geometry":{
"type":"Point","coordinates": [97973.4655999987,6219081.53249992,0]},
"properties":{
"ADDRESSAREA_resolved":"Sadelvägen",
"multi_reader_id":1,
"multi_reader_full_id":1,
"BALSTATUS_resolved":"Gällande",
"REMARKTYPE_resolved":"",
"FARMADDRESSAREA_resolved":"",
"geodb_type":"geodb_point",
"multi_reader_keyword":"GEODATABASE_SDE_2",
"DEVIATEFROMSTANDARD_resolved":"",
"geodb_feature_is_simple":"yes",
"STATUS_resolved":"Ingen information",
"ADDRESSEDCONSTRUCTIONTYPE_resolved":"",
"SUPPLIER_resolved":"",
"multi_reader_type":"GEODATABASE_SDE",
"geodb_oid":18396,
"STAIRCASEIDENTIFIER_resolved":"",
"LOCATIONADDRESSSTATUS_resolved":"Gällande",
"POSITIONKIND_resolved":"Byggnad",
"BALADDRESSTYPE_resolved":"Gatuadressplats",
"COMMENTARY":"","
DTYPE":"",
"EXTERNALID":2,"GID":"{DEEA1685-2FF3-4BEB-823D-B9FA51E09F71}",
"MODIFICATIONDATE":"20170301173751",
"MODIFICATIONSIGN":"BAL service",
"OBJECTID":18396,
"REGDATE":"20110321151134",
"REGSIGN":"BAL service",
"STATUS":0,
"ADDRESSEDCONSTRUCTIONVALUE":"",
"LABELROTATIONANGLE":0,
"POSTCODE":"25483",
"POSITIONKIND":1,
"REALPROPERTYKEY":"120320803",
"BALSTATUS":2,
"BALADDRESSTYPE":1,
"BALID":"D5650F0B-EE54-4C4C-9C40-A8162118288C",
"DESIGNATIONVALUE":"",
"SYNCDATE":"20170301173751",
"STREETNAME":"Sadelvägen",
"ADDRESSAREA":554,
"YARDSNAME":"",
"PLACENAMEID":"",
"ADDRESSLABEL":"Sadelvägen 6",
"DESIGNATIONNUMBERLETTER":"",
"LOCATIONADDRESSSTATUS":3,
"CITY":"Helsingborg",
"ENUMERATOR":"6",
"SYMBOLROTATIONANGLE":0,
"POPULARNAME":"",
"geodb_feature_dataset":"Adress"
}
}
}]
}

Answer 1

https://en.m.wikipedia.org/wiki/Transverse_Mercator_projection
Longitude of natural origin 0° 00' 00.000" N
13° 30' 00.000" E
Scale factor at natural origin
1
False easting
150000
meters
False northing
0
FINAL (Playground) version
//: [Previous](#previous)
import Foundation
extension Double {
var rad: Double {
get {
return .pi * self / 180.0
}
}
var deg: Double {
get {
return 180.0 * self / .pi
}
}
}
// SWEREF99 13 30 (GRS80)
let φ0 = 0.0
let λ0 = 13.5.rad
let N0 = 0.0
let E0 = 150000.0
let k0 = 1.0
// GRS80
let a = k0 * 6378137.0
let b = k0 * 6356752.31414034
let n = (a - b)/(a + b)
let n2 = n * n
let n3 = n2 * n
let n4 = n3 * n
let a2 = a * a
let b2 = b * b
let e2 = (a2 - b2)/a2
let H0 = 1.0 + 1.0/4.0*n2 + 1.0/64.0*n4
let H2 = -3.0/2.0*n + 3.0/16.0*n3
let H4 = 15.0/16.0*n2 - 15.0/64.0*n4
let H6 = -35.0/48.0*n3
let H8 = 315.0/512.0*n4
let ν:(Double)->Double = { φ in
return a/(sqrt(1.0 - e2 * sin(φ) * sin(φ)))
}
let ρ:(Double)->Double = { φ in
return ν(φ) * (1.0 - e2) / (1.0 - e2 * sin(φ) * sin(φ))
}
let η2:(Double)->Double = { φ in
return ν(φ) / ρ(φ) - 1.0
}
var arcMeridian1:(Double)->Double = { φ in
let m = (a + b) / 2 * (H0 * φ + H2 * sin(2.0 * φ) + H4 * sin(4.0 * φ) + H6 * sin(6.0 * φ) + H8 * sin(8.0 * φ))
return m
}
var arcMeridian:(Double, Double)->Double = { φ1, φ2 in
return arcMeridian1(φ2) - arcMeridian1(φ1)
}
var cartografic:(Double,Double)->(Double,Double) = { φ, λ in
let νφ = ν(φ)
let ρφ = ρ(φ)
let η2φ = νφ / ρφ - 1.0
let s1 = sin(φ)
let s2 = s1 * s1
let c1 = cos(φ)
let c2 = c1 * c1
let c3 = c2 * c1
let c5 = c3 * c2
let t2 = s2/c2
let t4 = t2 * t2
let k1 = νφ * c1
let k2 = νφ/2.0 * s1 * c1
let k3 = νφ/6.0 * c3 * (νφ / ρφ - t2)
let k4 = νφ/24.0 * s1 * c3 * (5.0 - t2 + 9.0 * η2φ)
let k5 = νφ/120.0 * c5 * (5.0 - 18.0 * t2 + t4 + 14.0 * η2φ - 58.0 * t2 * η2φ)
let k6 = νφ/720.0 * s1 * c5 * (61.0 - 58.0 * t2 + t4)
let Δλ = λ - λ0
let Δλ2 = Δλ * Δλ
let Δλ3 = Δλ2 * Δλ
let Δλ4 = Δλ3 * Δλ
let Δλ5 = Δλ4 * Δλ
let Δλ6 = Δλ4 * Δλ
let N = arcMeridian(φ0,φ) + N0 + Δλ2 * k2 + Δλ4 * k4 + Δλ6 * k6
let E = E0 + Δλ * k1 + Δλ3 * k3 + Δλ5 * k5
return (N,E)
}
var geodetic:(Double,Double)->(Double,Double) = { N, E in
var φ = (N - N0) / a + φ0
var M = arcMeridian(φ0, φ)
var diff = 1.0
repeat {
φ += (N - N0 - M) / a
M = arcMeridian(φ0, φ)
diff = N - N0 - M
} while abs(diff) > 0.0000000001 // max 3 - 4 iterations
let E1 = E - E0
let E2 = E1 * E1
let E3 = E2 * E1
let E4 = E3 * E1
let E5 = E4 * E1
let E6 = E5 * E1
let E7 = E6 * E1
let νφ = ν(φ)
let νφ3 = νφ * νφ * νφ
let νφ5 = νφ3 * νφ * νφ
let νφ7 = νφ5 * νφ * νφ
let ρφ = ρ(φ)
let η2φ = νφ / ρφ - 1.0
let s1 = sin(φ)
let s2 = s1 * s1
let c1 = cos(φ)
let t1 = s1 / c1
let t2 = t1 * t1
let t4 = t2 * t2
let t6 = t4 * t2
let k1 = 1.0 / (c1 * νφ)
let k2 = t1 / (2.0 * ρφ * νφ)
let k3 = 1.0 / (6.0 * νφ3) * (νφ / ρφ + 2.0 * t2)
let k4 = (t1 / (24.0 * ρφ * νφ3)) * (5.0 + 3.0 * t2 + η2φ - 9.0 * t2 * η2φ)
let k5 = 1.0 / (120.0 * νφ5) * (5.0 + 28.0 * t2 + 24.0 * t4)
let k6 = (t1 / (720.0 * ρφ * νφ5)) * (61.0 + 90.0 * t2 + 45.0 * t4)
let k7 = (t1 / (5040.0 * ρφ * νφ7)) * (61.0 + 662.0 * t2 + 1320.0 * t4 + 720.0 * t6)
φ = φ - E2 * k2 + E4 * k4 - E6 * k6
let λ = λ0 + E1 * k1 - E3 * k3 + E5 * k5 - E7 * k7
return (φ, λ)
}
print("pecision check")
let carto0 = cartografic(55.0.rad, 12.75.rad)
print(carto0,"err:", carto0.0 - 6097487.637, carto0.1 - 102004.871)
let carto1 = cartografic(61.0.rad, 14.25.rad)
print(carto1,"err:", carto1.0 - 6765725.847, carto1.1 - 190579.995)
print()
print("given position: N 6219081.53249992, E 97973.4655999987")
let geo = geodetic(6219081.53249992, 97973.4655999987)
print("geodetic: φ =", geo.0.deg,"λ =", geo.1.deg)
//: [Next](#next)
prints
pecision check
(6097487.6372101102, 102004.87085248799) err: 0.00021011009812355 -0.000147512007970363
(6765725.8471242301, 190579.99493182387) err: 0.000124230049550533 -6.81761302985251e-05
given position: N 6219081.53249992, E 97973.4655999987
geodetic: φ = 56.0916410844269 λ = 12.6641326192406
position on map

Answer 2

I dont understand what are you looking for exactly but what I would do (since you are using swift) is create an extension of MKPointAnnotation and add a new initialiser that takes the geoJSON, parse it, fetch the coordinates (and whatever data you intend to put in the annotation object) and return a MKPointAnnotation with the required data.
just incase you dont know how to parse a JSON here s an example :
do {
let dictionary = try JSONSerialization.jsonObject(with: geoJSON!,
options: JSONSerialization.ReadingOptions.mutableContainers) as! [String: AnyObject]
let features = dictionary["features"] as! [[String:AnyObject]]
let geometry = features[0]["geometry"] as! [String: AnyObject]
....
}catch{
//incase the json doesnt get parsed
}
keep going until you reach the coordinates ..;
obviously dont use force cast incase you are hesitate about a value instead use guard or if let ....