How come I need to pass variables this struct when I declare it in Swift?

I would advice to change your Model struct to:

struct SV_StinkDetails_Model{
    var SV_StinkDetails_Description:String
    var SV_StinkDetails_RecordingDate:NSDate
    var SV_StinkDetails_Location :SV_StinkLocation_Model?
}

You don’t have to declare values since you use the default init (neither do you need to declare them if you use a custom init)
In the struct I placed above your Location_Model is a optional, this means you can set the initial value to “nil”. Later you can add this info. Remember to check (with a “if let” statement) if the value is set whenever you try to access it though!

For added value:
You don’t need to put the “!” behind your type declarations in the Model struct.

If you change these 2 things you can get your new class using:

import Foundation
import UIKit
import CoreData
import AVFoundation
import CoreLocation

struct SV_StinkLocation_Model{
    var SV_StinkLocation_Longitude:NSNumber
    var SV_StinkLocation_Latitude:NSNumber
    var SV_StinkLocation_Suburb:String
    var SV_StinkLocation_State:String
    var SV_StinkLocation_Country:String
}

struct SV_StinkDetails_Model{
    var SV_StinkDetails_Description:String
    var SV_StinkDetails_RecordingDate:NSDate
    var SV_StinkDetails_Location :SV_StinkLocation_Model?
}

var details_model = SV_StinkDetails_Model(SV_StinkDetails_Description: "Description:", SV_StinkDetails_RecordingDate: NSDate(), SV_StinkDetails_Location: nil)

details_model.SV_StinkDetails_Location = SV_StinkLocation_Model(SV_StinkLocation_Longitude: 1, SV_StinkLocation_Latitude: 1, SV_StinkLocation_Suburb: “Suburb", SV_StinkLocation_State: "State", SV_StinkLocation_Country: "Country")

Lastly you can access let’s say the longtitude of the option value using:

if let longtitude =  details_model.SV_StinkDetails_Location?.SV_StinkLocation_Longitude {
    println(longtitude)
}