Send Value of a variable from view to class - SwiftUI - swiftui

Question

What I am trying to do is send the value of a variable from a view to a class, but I keep getting an error. Not sure what to do.
Here is the class:
class perfCalcDep: ObservableObject {
var tom:Double
var arm:Double
#Published var tempDep:String = ""
#Published var elevDep:String = ""
#Published var qnhDep:String = ""
#Published var windDep:String = ""
#Published var slopeDep:String = ""
#Published var rwyCondDep = 0
var altDep: Double {
let pressCalc = (1013 - (Double(qnhDep) ?? 1013)) * 30
return (Double(elevDep) ?? 0) + pressCalc
}
var altVar : Double { 0.21 * altDep }
var tempVar : Double { 24 * (Double(tempDep) ?? 0) }
var windVar : Double { 20.67 * (Double(windDep) ?? 0) }
var tomVar : Double { 2.22 * Double(2550-Double(tom)) }
var slpVar : Double { (Double(slopeDep) ?? 0) / 2 }
var tod : Double { (1700 + altVar + tempVar - tomVar - windVar) }
var todr : Double {
if rwyCondDep == 1 {
return (tod + ((0.1 * tod) * slpVar)) * 1.2
} else if rwyCondDep == 2 {
return (tod + ((0.1 * tod) * slpVar)) * 1.3
} else {
return (tod + ((0.1 * tod) * slpVar))
}
}
init(tom:Double, arm:Double) {
self.tom = tom
self.arm = arm
}
}
And here is part of the view:
struct TakeOffPerf: View {
// The variables I want to send to the class - their values are received from the previous view.
var tMss:Double
var tArm:Double
#ObservedObject var performance = perfCalcDep(tom: tMss, arm: tArm) // Error: Cannot use instance member 'tArm' within property initializer; property initializers run before 'self' is available
#ObservedObject var settings = Settings()
var body: some View {,,,} // just a list that shows the values from the class
Any help would be greatly appreciated.

Answer 1

Properties are initialised before self, so you cannot make initializing dependency between properties, but you can do this in init, eg.
struct TakeOffPerf: View {
var tMss:Double
var tArm:Double
#ObservedObject var performance: perfCalcDep // << only declare !!
#ObservedObject var settings = Settings()
init(tMss:Double, tArm:Double) {
self.tArm = tArm
self.tMss = tMss
self.performance = perfCalcDep(tom: tMss, arm: tArm)
}
// ... other code
}
Note: preserved original style, but it is good practice to name types capitalised, like PerfCalcDep