CODEWITHSUNDEEP
iosswiftcore-plot
lktlktlkt
lktlktlkt

Reputation: 51

Call Function in Different Class in Swift(fatal error)?

I have a class which is for bluetooth data receiving and I wonder to send the receiving data to class UIViewController and do the realtime plotting(CorePlot)

class BluetoothManager: NSObject {
   func dataReceiving(value: [Int]){
      for (var m=0 ; m<5 ; m++){
         dataOne[m] = value[2*m]
         dataTwo[m] = value[2*m+1] 
      }
   MainController().plot(dataOne: [Int], dataTwo: [Int])
}

MainController class:

class MainController: UIViewController,CPTScatterPlotDataSource {

    @IBOutlet weak var graphView: CPTGraphHostingView!

    private var scatterGraph : CPTXYGraph? = nil
    typealias plotDataType = [CPTScatterPlotField : Double]
    private var dataForPlot = [plotDataType]()

    func plot(dataOne: [Int], dataTwo: [Int]){
        let newGraph = CPTXYGraph(frame: CGRectZero)
        graphView.hostedGraph = newGraph
        ...
    }
}

When the procedure goes to graphView.hostedGraph = newGraph , there will have a fatal error:

unexpectedly found nil while unwrapping an Optional value

I have tried call the plot function in the MainController class, it was worked!

Can anybody help me to fix this problem? Thanks!

Upvotes: 0

Views: 333

Answers (3)

vadian
vadian

Reputation: 285082

MainController() creates a new instance of the MainController class which is different from the object in Interface Builder.

You need the reference to the MainController object in Interface Builder

Upvotes: 0

luk2302
luk2302

Reputation: 57124

You are creating a new instance of the MainController in the line

MainController().plot(dataOne: [Int], dataTwo: [Int])

Therefore the @IBOutlet weak var graphView: CPTGraphHostingView! is nil - therefore your code crashes.

You must not create a new instance of the MainController the way you currently do - either instantiate it via the storyboard, or pass in the correct nib file. For both cases you have to set the MainController as controller class in the IB and connect the outlet.

Upvotes: 1

Dennis Weidmann
Dennis Weidmann

Reputation: 1967

you have declared plot as an instance method, and you are calling it as a class method.

You need to change this line:

func plot(dataOne: [Int], dataTwo: [Int]){

To this line:

class func plot(dataOne: [Int], dataTwo: [Int]){

If you need to call it like you do it

Upvotes: 0

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