Could not register the selector of the member because the selector is already registered on a different member

Question

Currently, I am trying to bind the Qualtrics library for the Xamarin.iOS project and I did it but when I run the project then application crashed and it is saying that

Error : "Could not register the selector 'userContentController:didReceiveScriptMessage:' of the member 'QualtricsIos.QualtricsSurveyViewController.UserContentController' because the selector is already registered on the member 'DidReceiveScriptMessage'.

Could not register the selector 'initWithCoder:' of the member 'QualtricsIos.QualtricsSurveyViewController..ctor' because the selector is already registered on the member 'ConstructorCoder'.

I have tried the solution which is similar to it but no luck till now. I have checked the ApiDefinitions and StructsAndEnums as well I did not find the root cause. Can anyone tell me what is wrong?

ApiDefinitions File:

namespace QualtricsLib
{
    // @interface InitializationResult : NSObject
    [BaseType(typeof(NSObject))]
    [Protocol]
    [DisableDefaultCtor]
    interface InitializationResult
    {
        // -(NSString * _Nullable)getMessage __attribute__((warn_unused_result));
        [NullAllowed, Export("getMessage")]

        string Message { get; }

        // -(BOOL)passed __attribute__((warn_unused_result));
        [Export("passed")]

        bool Passed { get; }
    }

// @interface Properties : NSObject
[BaseType(typeof(NSObject))]
[Protocol]
interface Properties
{
    // -(void)setStringWithString:(NSString * _Nonnull)string for:(NSString * _Nonnull)key;
    [Export("setStringWithString:for:")]
    void SetStringWithString(string @string, string key);

    // -(void)setNumberWithNumber:(double)number for:(NSString * _Nonnull)key;
    [Export("setNumberWithNumber:for:")]
    void SetNumberWithNumber(double number, string key);

    // -(void)setDateTimeFor:(NSString * _Nonnull)key;
    [Export("setDateTimeFor:")]
    void SetDateTimeFor(string key);
}

// @interface Qualtrics : NSObject
[BaseType(typeof(NSObject))]
[Protocol]
[DisableDefaultCtor]
interface Qualtrics
{
    // @property (readonly, nonatomic, strong, class) Qualtrics * _Nonnull shared;
    [Static]
    [Export("shared", ArgumentSemantic.Strong)]
    Qualtrics Shared { get; }

    // @property (readonly, nonatomic, strong) Properties * _Nonnull properties;
    [Export("properties", ArgumentSemantic.Strong)]
    Properties Properties { get; }

    // -(void)initializeWithBrandId:(NSString * _Nonnull)brandId zoneId:(NSString * _Nonnull)zoneId interceptId:(NSString * _Nonnull)interceptId completion:(void (^ _Nullable)(InitializationResult * _Nonnull))completion;
    [Export("initializeWithBrandId:zoneId:interceptId:completion:")]
    void InitializeWithBrandId(string brandId, string zoneId, string interceptId, [NullAllowed] Action<InitializationResult> completion);

    //-(void) evaluateTargetingLogicWithCompletion:(void (^ _Nonnull)(TargetingResult* _Nonnull))completion;
    [Export("evaluateTargetingLogicWithCompletion:")]
    void EvaluateTargetingLogicWithCompletion(Action<TargetingResultNew> completion);

    // -(BOOL)handleLocalNotificationWithResponse:(UNNotificationResponse * _Nonnull)response displayOn:(UIViewController * _Nonnull)viewController __attribute__((availability(ios, introduced=10.0))) __attribute__((warn_unused_result));
    //[iOS(10, 0)]
    [Export("handleLocalNotificationWithResponse:displayOn:")]
    bool HandleLocalNotificationWithResponse(UNNotificationResponse response, UIViewController viewController);

    // -(BOOL)handleLocalNotification:(UILocalNotification * _Nonnull)notification displayOn:(UIViewController * _Nonnull)viewController __attribute__((warn_unused_result));
    [Export("handleLocalNotification:displayOn:")]
    bool HandleLocalNotification(UILocalNotification notification, UIViewController viewController);

    // -(BOOL)displayWithViewController:(UIViewController * _Nonnull)viewController __attribute__((warn_unused_result));
    [Export("displayWithViewController:")]
    bool DisplayWithViewController(UIViewController viewController);

    // -(void)displayTargetWithTargetViewController:(UIViewController * _Nonnull)targetViewController targetUrl:(NSString * _Nonnull)targetUrl;
    [Export("displayTargetWithTargetViewController:targetUrl:")]
    void DisplayTargetWithTargetViewController(UIViewController targetViewController, string targetUrl);

    // -(BOOL)hide __attribute__((warn_unused_result));
    [Export("hide")]
    bool Hide { get; }

    // -(void)registerViewVisitWithViewName:(NSString * _Nonnull)viewName;
    [Export("registerViewVisitWithViewName:")]
    void RegisterViewVisitWithViewName(string viewName);

    // -(void)resetTimer;
    [Export("resetTimer")]
    void ResetTimer();

    // -(void)resetViewCounter;
    [Export("resetViewCounter")]
    void ResetViewCounter();
}

//@interface QualtricsSurveyViewController : UIViewController<WKScriptMessageHandler>
[BaseType(typeof(UIViewController))]
[Protocol]
[DisableDefaultCtor]
interface QualtricsSurveyViewController : IWKScriptMessageHandler
{
    // -(instancetype _Nonnull)initWithUrl:(NSString * _Nonnull)url __attribute__((objc_designated_initializer));
    [Export("initWithUrl:")]
    [DesignatedInitializer]
    IntPtr Constructor(string url);

    // -(instancetype _Nullable)initWithCoder:(NSCoder * _Nonnull)aDecoder __attribute__((objc_designated_initializer));

    [Export("initWithCoder:")]
    [DesignatedInitializer]
    //[Static]
    IntPtr ConstructorCoder(NSCoder aDecoder);

    // -(void)viewDidAppear:(BOOL)animated;
    [Export("viewDidAppear:")]
    void ViewDidAppear(bool animated);

    // -(void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator> _Nonnull)coordinator;
    [Export("viewWillTransitionToSize:withTransitionCoordinator:")]
    void ViewWillTransitionToSize(CGSize size, IUIViewControllerTransitionCoordinator coordinator);

    // -(void)userContentController:(WKUserContentController * _Nonnull)userContentController didReceiveScriptMessage:(WKScriptMessage * _Nonnull)message;
    [Export("userContentController:didReceiveScriptMessage:")]
    //[Static]
    void UserContentController(WKUserContentController userContentController, WKScriptMessage message);
}

// @interface TargetingResult : NSObject
[BaseType(typeof(NSObject))]
[Protocol]
[DisableDefaultCtor]
interface TargetingResultNew
{
    // -(NSString * _Nullable)getSurveyUrl __attribute__((warn_unused_result));
    [NullAllowed, Export("getSurveyUrl")]

    string SurveyUrl { get; }

    // -(enum targetingResultStatus)getTargetingResult __attribute__((warn_unused_result));
    [Export("getTargetingResult")]

    TargetingResultStatus TargetingResult { get; }

    // -(BOOL)passed __attribute__((warn_unused_result));
    [Export("passed")]

    bool Passed { get; }

    // -(TargetingResultError * _Nullable)getError __attribute__((warn_unused_result));
    [NullAllowed, Export("getError")]

    TargetingResultError Error { get; }

    // -(void)recordImpression;
    [Export("recordImpression")]
    void RecordImpression();

    // -(void)recordClick;
    [Export("recordClick")]
    void RecordClick();
}

// @interface TargetingResultError : NSObject
[BaseType(typeof(NSObject))]
[Protocol]
[DisableDefaultCtor]
interface TargetingResultError
{
}

}

StructsAndEnums File:

namespace QualtricsLib
{
    [Native]
    public enum TargetingResultStatus : long
    {
        Passed = 0,
        FailedLogic = 1,
        SampledOut = 2,
        MultipleDisplayPrevented = 3,
        Error = 4
    }
}

Answer 1

I fixed that issue by removing the initWithCoder method QualtricsSurveyViewController and remove the inheritance. this option fixed the selector issue but it throws the object reference not set to an instance of an object exception when running the application.

I look into the header file and found the SWIFT_CLASS name in the header like

SWIFT_CLASS("_TtC9Qualtrics29QualtricsSurveyViewController")

So, The same thing I applied to the ApiDefinitions file

[BaseType(typeof(UIViewController), Name = "_TtC9Qualtrics29QualtricsSurveyViewController")]

And bingo!! it is working!!!

This solution has fixed my all the issue and binding library is successfully working.