인프런 커뮤니티 질문&답변

강의 수강 중 35분 정도까지 따라한 뒤 실행했는데, 다음 에러가 발생했는데 이유를 잘 모르겠습니다.

다음처럼 에러가 발생하였는데요. 에러 내용과 작성한 코드들 첨부드립니다.

Exception	NSException *	"-[UITextField setDataSource:]: unrecognized selector sent to instance 0x107079600"	0x0000600000c9d170

에러 전체 내용

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UITextField setDataSource:]: unrecognized selector sent to instance 0x107079600'
*** First throw call stack:
(
	0   CoreFoundation                      0x00000001804b70ec __exceptionPreprocess + 172
	1   libobjc.A.dylib                     0x000000018008ede8 objc_exception_throw + 72
	2   CoreFoundation                      0x00000001804ccc54 +[NSObject(NSObject) instanceMethodSignatureForSelector:] + 0
	3   UIKitCore                           0x0000000185ace7a8 -[UIResponder doesNotRecognizeSelector:] + 232
	4   CoreFoundation                      0x00000001804bb3ec ___forwarding___ + 1268
	5   CoreFoundation                      0x00000001804bdb0c _CF_forwarding_prep_0 + 92
	6   CurrencyConverterApp.debug.dylib    0x000000010508d1ec $s20CurrencyConverterApp20PickerViewControllerC11viewDidLoadyyF + 648
	7   CurrencyConverterApp.debug.dylib    0x000000010508d270 $s20CurrencyConverterApp20PickerViewControllerC11viewDidLoadyyFTo + 36
	8   UIKitCore                           0x000000018533369c -[UIViewController _sendViewDidLoadWithAppearanceProxyObjectTaggingEnabled] + 80
	9   UIKitCore                           0x0000000185338238 -[UIViewController loadViewIfRequired] + 908
	10  UIKitCore                           0x000000018529db34 -[UINavigationController _ensureToViewControllersViewIsLoaded:] + 84
	11  UIKitCore                           0x000000018529df70 -[UINavigationController transitionConductor:willTransitionFromViewController:toViewController:] + 184
	12  UIKitCore                           0x0000000185c35c70 -[_UIViewControllerTransitionConductor startDeferredTransitionIfNeeded] + 452
	13  UIKitCore                           0x00000001852951a4 -[UINavigationController __viewWillLayoutSubviews] + 80
	14  UIKitCore                           0x000000018527cf58 -[UILayoutContainerView layoutSubviews] + 168
	15  UIKitCore                           0x000000018601c0c4 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2404
	16  QuartzCore                          0x000000018b06ceb0 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 432
	17  QuartzCore                          0x000000018b077c34 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 124
	18  QuartzCore                          0x000000018afacc58 _ZN2CA7Context18commit_transactionEPNS_11TransactionEdPd + 464
	19  QuartzCore                          0x000000018afdb468 _ZN2CA11Transaction6commitEv + 652
	20  UIKitCore                           0x0000000185abb7b4 __34-[UIApplication _firstCommitBlock]_block_invoke_2 + 32
	21  CoreFoundation                      0x000000018041b0ec __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 20
	22  CoreFoundation                      0x000000018041a824 __CFRunLoopDoBlocks + 352
	23  CoreFoundation                      0x00000001804150c8 __CFRunLoopRun + 812
	24  CoreFoundation                      0x0000000180414960 CFRunLoopRunSpecific + 536
	25  GraphicsServices                    0x0000000190183b10 GSEventRunModal + 160
	26  UIKitCore                           0x0000000185aa2b40 -[UIApplication _run] + 796
	27  UIKitCore                           0x0000000185aa6d38 UIApplicationMain + 124
	28  UIKitCore                           0x0000000184e9a184 block_destroy_helper.22 + 9660
	29  CurrencyConverterApp.debug.dylib    0x000000010508820c $sSo21UIApplicationDelegateP5UIKitE4mainyyFZ + 120
	30  CurrencyConverterApp.debug.dylib    0x0000000105088184 $s20CurrencyConverterApp0C8DelegateC5$mainyyFZ + 44
	31  CurrencyConverterApp.debug.dylib    0x0000000105088288 __debug_main_executable_dylib_entry_point + 28
	32  dyld                                0x00000001050dd410 start_sim + 20
	33  ???                                 0x0000000104e1e274 0x0 + 4376879732
)
libc++abi: terminating due to uncaught exception of type NSException

AppDelegate.swift

//
//  AppDelegate.swift
//  CurrencyConverterApp
//
//  Created by hojeongpark on 9/24/24.
//

import UIKit

@main
class AppDelegate: UIResponder, UIApplicationDelegate {



    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

    // MARK: UISceneSession Lifecycle

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
        // Called when the user discards a scene session.
        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    }


}

PickerViewController.swift

//
//  ViewController.swift
//  CurrencyConverterApp
//
//  Created by hojeongpark on 9/24/24.
//

import UIKit

class PickerViewController: UIViewController {
    var rates: [(String, Double)]?
    
    @IBOutlet weak var currencyPicker: UIPickerView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        self.navigationItem.title = "Currency List"
        
        currencyPicker.delegate = self
        currencyPicker.dataSource = self
        
        fetchJson()
    }

    
    func fetchJson() {
        let urlString = "https://open.er-api.com/v6/latest/USD"
        guard let url = URL(string: urlString) else {
            return
        }
        
        print("fetchJson")
        
        // data task
        
        URLSession.shared.dataTask(with: url) { data, response, error in
            guard let data = data else {
                return
            }
            
            do {
                let currencyModel = try JSONDecoder().decode(CurrencyModel.self, from: data)
                
                self.rates = currencyModel.rates?.sorted{ $0.key < $1.key }
                
                // 피커 새로고침 해야 데이터 내용이 보입니다.
                DispatchQueue.main.async {
                    self.currencyPicker.reloadAllComponents()
                }
                
                print("currencyModel", currencyModel)
            }catch{
                print("error", error)
            }
            
        }.resume()
    
    }
}


extension PickerViewController: UIPickerViewDelegate, UIPickerViewDataSource {
    
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }
    
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return rates?.count ?? 0
    }
    
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return rates?[row].0
    }
    
    
}