How to call a function from another controller in swift

user_4030015 0
Viewed 3193

I set the Show Charts button on the DetailView Controller which triggers the getChartData function and shows me the values in display view in charts, now I want to call that function in the didselectrow on the main Viewcontroller so that the chart is loaded automatically, but it fails. When I tried to call that function in didselectrow (DVC.getChartsData) I got the error "Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value"

DVC.getChartsData

Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value

ViewController:

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {        
        let Storyboard = UIStoryboard(name: "Main", bundle: nil)
        let DVC = Storyboard.instantiateViewController(withIdentifier: "DetailViewController") as! DetailViewController
        DVC.getDetailName = coin[indexPath.row].name
        let formatedRoundingPrice = (coin[indexPath.row].price as NSString).floatValue * currencymodel.indexValue
        let formatedPrice = String (format: "%.3f", formatedRoundingPrice)
        DVC.getDetailPrice = formatedPrice
        self.navigationController?.pushViewController(DVC, animated: true)
        let percentage = String ((coin[indexPath.row].percent as NSString).floatValue)
        DVC.getDetailPercent = percentage
        tableView.deselectRow(at: indexPath, animated: true)
        //DVC.getChartData()
}

DetailViewController:

    @IBAction func tapLineChart(_ sender: Any) {


       getChartData()


    }

    func getChartData () {

        let chart = HITLineChartView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: displayView.bounds.height))
        displayView.addSubview(chart)
        let max = String((priceResult.max() ?? 0.0).rounded(.up))
        let min = String((priceResult.min() ?? 0.0).rounded(.down))
        let maxChange = abs((listOfChanges.max()) ?? 0.0).rounded(.up)
        let minChange = abs((listOfChanges.min()) ?? 0.0).rounded(.up)
        absMaxPercentage = Int(maxChange > minChange ? maxChange : minChange)
        titles = ["\(getDetailName) closing price is \(getDetailPrice)"]

        print(data)
        chart.draw(absMaxPercentage,
                   values: listOfChanges,
                   label: (max: max, center: "", min: min),
                   dates: namesArray,
                   titles: titles)

        addCloseEvent(chart)

        finalURL = baseURL + "bitcoin" + "/market_chart?vs_currency=usd&days=5"
        print(finalURL)
        getBitcoinData(url: finalURL)

    }

How to load my charts tap on a specific tableview cell instead of tapping on tapLineChart.

https://imgur.com/fg2502P

https://imgur.com/C4AzaRY

https://imgur.com/jOrwujy

didselectrowatindexpath swift uiviewcontroller function
2 Answers

if you want to call a function on viewControllerB that you declare from viewController A.

just create the object of the class file you want to use the function from

var obj mainVC = MainViewController()



class MainViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }
    func commonMethod() {
        print("From the main class")
    }
}

Using that object, call the function in another file where you mean to use it

class OtherViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        mainVC.commonMethod()
        // Do any additional setup after loading the view, typically from a nib.
    }
}

Additionally, You can also create a new swift file, name it Global.swift, create all your functions that you want to use throughout the application here. They become "global functions"

user_82726980

You will want to use delegates or observers to pass data between view controllers.

I'm new to tutorials, but I wrote a bit about this here: https://www.eankrenzin.com/swift-blog/pass-data-throughout-your-app-with-observers-and-notifications-xcode-11-amp-swift-5

You should use optional binding to unwrap your VC let DVC = Storyboard.instantiateViewController(withIdentifier: "DetailViewController") as! DetailViewController

Your code is crashing because of that line. Check your interface builder to make sure the identifier is correct. Edit: this line was not causing a crash, but it is still better to use optional binding.The line is: https://imgur.com/CVP1x6H

NOTE: It is terrible practice to litter your app with instances when delegates and observers could work. Also do NOT have globals. Globals are disastrous for debugging and create tech debt.

user_89431080
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