translating CLLocation coordinates into SCNVector3 matrics - ios

Question

Goal: Have a AR item fixed to a location in real world based on CLLocation coordinates (LLA), and have it in the same place regardless of my orientation on viewload.
Ive been trying to convert geo LLA coordinates into an SCNVector3 matrix. The issues im having are as followed:
1) Lat1 and Long1 are based on my current coordinates from a CLLocationManager on my device. Im looking for a way to get the relative SCNVector3[x,y,z] needed by my device to and place an item at lat2 and long2's location in the real world.
2) How do I get this targeted Lat2, Long2 to be in the same place every time. I feel like the alignment of . gravityAndHeading isn't working to always orient the matrix facing true north. So though sometimes I may get the correct distance from my device location, the orientation is off.
3) I would like the values to be accurate enough to recognize something at least 2-3 meters away. even when i manually program the SCNVector3 from the same position, it seems a bit off.
Any guidance would be greatly appreciated. I've already looked at http://www.mathworks.com/help/aeroblks/llatoecefposition.html and http://www.jaimerios.com/?p=39 but it seems to return the distance but not the relative position to the phone in an SCNVector format.
import SceneKit
import ARKit
import CoreLocation
...
func latLonToECEF(_ lat1: Double,_ lon2: Double,_ alt: Double?) -> [String:Double] {
let x = 6371 * cos(lat1) * cos(long1)
let y = 6371 * cos(lat1) * sin(long1)
let z = 6371 * sin(lat1)
let lat2 = static_lat
let long2 = static_long
let x2 = 6371 * cos(lat2) * cos(long2)
let y2 = 6371 * cos(lat2) * sin(long2)
let z2 = 6371 * sin(lat2)
return ["x": (x2 - x), "y": (y2 - y), "z": (z2 - z)]
}