I have checked the other case on this but lazy var doesn't seem to fix my problem here.
I have this code I am using to solve a certain equation and, once it's solved, I want to return the 2 arrays I get as answers back to my original code in ViewController.swift. The code is given below but, at the line where I try to actually solve the problem with let (dollars1, dollars2) = prob.solveUsingSolver(solver:solveEuler) line. I was initially testing it in the playground with just prob.solveUsingSolver(solver:solveEuler), which solved the problem. But, in the main application, it's giving an "Expected declaration" error. And if I try to assign the outputs to dollars1 and dollars2, I get the
Cannot use instance member 'prob' within property initializer; property initializers run before 'self' is available
import Charts
class ViewController: UIViewController, ChartViewDelegate {
@IBOutlet weak var lineChartView: LineChartView!
override func viewDidLoad()
{
super.viewDidLoad()
// Solving the problem
let wholearray = HE(Th1: 100.0, Tc2: 25.0, deltaZ: 0.1).solveUsingSolver(solver:solveEuler)
let temp_hot = wholearray.xarray
let temp_cold = wholearray.varray
// 1
self.lineChartView.delegate = self
// 2
self.lineChartView.chartDescription?.text = "Tap node for details"
// 3
self.lineChartView.descriptionTextColor = UIColor.white
self.lineChartView.gridBackgroundColor = UIColor.darkGray
// 4
self.lineChartView.noDataText = "No data provided"
// 5
setChartData(space_dimensionless: space_dimensionless)
}
let space_dimensionless = [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]
typealias Solver = (Double, Double, Double) -> (Array<Double>, Array<Double>)
struct HE {
var Th1 = 0.0
var Tc2 = 0.0
var deltaZ = 0.0
init(Th1: Double, Tc2: Double, deltaZ: Double) {
self.Th1 = Th1
self.Tc2 = Tc2
self.deltaZ = deltaZ
}
func solveUsingSolver(solver: Solver) {
solver(Th1, Tc2, deltaZ)
}
}
func solveEuler(Th1: Double, Tc2: Double, z : Double) -> (xarray:Array<Double>, varray:Array<Double>)
{
var x = Th1
var i = 0.0
var upper = Th1
var lower = Tc2
var vold = (lower + upper) / 2
var v = vold
var xold = x
let epsilon = 0.05
var err = 1.0
var xarray: [Double] = [0,1,2,3,4,5,6,7,8,9,10]
var varray: [Double] = [0,1,2,3,4,5,6,7,8,9,10]
var j=0
while (err > epsilon) {
while i < 1 {
v -= 4*z*i*(xold-vold)
x -= z*i*(xold-vold)
xold = x
vold = v
i+=z
xarray[j]=x
varray[j]=v
j += 1
}
err = abs(varray[10] - Tc2)
if varray[10] > Tc2 {
upper = varray[0]
}
else {
lower = varray[0]
}
x = Th1
xold = x
vold = (lower + upper) / 2
v = vold
i=0.0
j=0
}
return (xarray,varray)
}
func setChartData(space_dimensionless : [Double]) {
// 1 - creating an array of data entries
var yVals1 : [ChartDataEntry] = [ChartDataEntry]()
for i in 0 ..< space_dimensionless.count {
yVals1.append(ChartDataEntry(x: space_dimensionless[i], y: temp_hot[i]))
}
// 2 - create a data set with our array
let set1: LineChartDataSet = LineChartDataSet(values: yVals1, label: "Hot Fluid")
set1.axisDependency = .left // Line will correlate with left axis values
set1.setColor(UIColor.red.withAlphaComponent(0.5)) // our line's opacity is 50%
set1.setCircleColor(UIColor.red) // our circle will be dark red
set1.lineWidth = 2.0
set1.circleRadius = 0.0 // the radius of the node circle
set1.fillAlpha = 65 / 255.0
set1.fillColor = UIColor.red
set1.highlightColor = UIColor.white
set1.drawCircleHoleEnabled = false
// 3 - creating an array of data entries
var yVals2 : [ChartDataEntry] = [ChartDataEntry]()
for i in 0 ..< space_dimensionless.count {
yVals2.append(ChartDataEntry(x: space_dimensionless[i], y: temp_cold[i]))
}
// 4 - create a data set with our array
let set2: LineChartDataSet = LineChartDataSet(values: yVals2, label: "Cold Fluid")
set2.axisDependency = .left // Line will correlate with left axis values
set2.setColor(UIColor.blue.withAlphaComponent(0.5)) // our line's opacity is 50%
set2.setCircleColor(UIColor.blue) // our circle will be dark red
set2.lineWidth = 2.0
set2.circleRadius = 0.0 // the radius of the node circle
set2.fillAlpha = 65 / 255.0
set2.fillColor = UIColor.blue
set2.highlightColor = UIColor.white
set2.drawCircleHoleEnabled = true
//5 - create an array to store our LineChartDataSets
var dataSets = [IChartDataSet]()
dataSets.append(set1)
dataSets.append(set2)
let lineChartData = LineChartData(dataSets: dataSets)
//6 - set our data
lineChartView.data = lineChartData
//7 Format chart more
self.lineChartView.xAxis.drawGridLinesEnabled = false
self.lineChartView.xAxis.labelPosition = XAxis.LabelPosition.bottom
self.lineChartView.xAxis.labelFont = UIFont(name: "HelveticaNeue-Light", size: 10.0)!
self.lineChartView.xAxis.labelTextColor = UIColor.black
self.lineChartView.xAxis.drawAxisLineEnabled=true
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
