Xamarin iOS中没有参数的绑定方法

Question

I started migrating my iOS app to unified API, however I am having some issues with the binding project. It happens that some of the delegate methods don't require parameters:

-(void) didFinishSendMail;

So, when I try to generate the binding, an error about a required parameter is shown so I add a fake param:

[Export ("didFinishSendMail")]
void DidFinishSendMail (bool fakeArg);

Then the binding project compiles ok and only some warnings are displayed.

However in the main project an error is displayed:

Error MT4117: The registrar found a signature mismatch in the method 'MITiOS_Binding64.MITIntegration/_MITIntegrationDelegate.DidFinishSendMail' - the selector 'didFinishSendMail' indicates the method takes 0 parameters, while the managed method has 1 parameters. (MT4117)

In previous version of Xamarin iOS and before migrating to Unified API I was able to add --registrar:legacy and the main project compiled with no problems, but now this registrar is not compatible with unified API.

So the question is, what is the way to bind a delegate method that takes no parameters using unified API?

Api Definition added:

[Model,Protocol,Preserve, BaseType (typeof (NSObject), Name = "MITIntegrationDelegate")]
public partial interface MITIntegrationDelegate {


    [Export ("didFinishCommandWithError:"), EventArgs("MitError")][Abstract]
    void DidFinishCommandWithError (MITError error);


    [Export ("didFinishTransaction:"), EventArgs("MitTransaction")][Abstract]
    void DidFinishTransaction (MITTransaction transaction);


    [Export ("didFinishCardReader:"), EventArgs("MitCardInformation")][Abstract]
    void DidFinishCardReader (MITCardInformation cardInformation);


    [Export ("didFinishTransactionWithMerchant:"), EventArgs("Merchants")][Abstract]
    void DidFinishTransactionWithMerchant (NSMutableArray merchants);


    [Export ("didFinishTransactionWithMerchant:merchantsMCI:merchantsMSI:error:"), EventArgs("MerchantsPDC")][Abstract]
    void DidFinishTransactionWithMerchantPDC (NSMutableArray merchantsPDC, NSMutableArray merchantsMCI, NSMutableArray merchantsMSI, MITError error);

    [Export ("didFinishTransactionWithLocalDccOption:andForeignDccOption:"), EventArgs("LocalDccOption")][Abstract]
    void DidFinishTransactionWithLocalDccOption(MITDccOption localOption, MITDccOption foreignOption);

    [Export ("onReturnEmvApplications:"), EventArgs("EmvApplications")][Abstract]
    void OnReturnEmvApplications (NSMutableArray applicationArray);

    [Export ("didFinishSendMailWithError:"), EventArgs("MitError")]
    void DidFinishSendMailWithError (MITError error);

    [Export ("didFinishSendElectronicBillWithMessage:error:"), EventArgs("SendElectronicBill")][Abstract]
    void DidFinishSendElectronicBillWithMessage (string message, MITError error);

    [Export ("didFinishSendMail"), EventArgs("Fake")]
    void DidFinishSendMail (bool fakeArg);

    [Export ("didFinishUploadSignature:"), EventArgs("Fake")]
    void DidFinishUploadSignature (bool fakeArg);

    [Export ("didFinishUploadSignatureWithError:"), EventArgs("MitError")]
    void DidFinishUploadSignatureWithError (MITError error);

    [Export ("onNoDeviceDetected:"), EventArgs("Fake")]
    void OnNoDeviceDetected (bool fakeArg);

    [Export ("onWaitingForCard:"), EventArgs("Fake")]
    void OnWaitingForCard (bool fakeArg);

    [Export ("onDeviceUnplugged:"), EventArgs("Fake")]
    void OnDeviceUnplugged (bool fakeArg);

    [Export ("onRequestTextInfo:"), EventArgs("RequestTextInfo")]
    void OnRequestTextInfo (string textInfo);


    [Export ("onReturnWalkerUid:newUid:"), EventArgs("ReturnWalkerUid")]
    void OnReturnWalkerUid (string uid, string newUid);


    [Export ("onReturnWalkerBatteryLevel:"), EventArgs("ReturnBatteryLevel")]
    void OnReturnWalkerBatteryLevel (string batteryLevel);


    [Export ("onReturnTransactions:error:"), EventArgs("ReturnTransactions")]
    void OnReturnTransactions (NSArray transactions, MITError error);
}

[BaseType (typeof (NSObject),Name = "MITIntegration", Delegates=new string [] { "WeakDelegate" }, 
    Events=new Type [] { typeof (MITIntegrationDelegate)})]
public partial interface MITIntegration {

    [Export ("delegate", ArgumentSemantic.Assign)]
    NSObject WeakDelegate { get; set; }

    [Wrap ("WeakDelegate"), NullAllowed]
    MITIntegrationDelegate Delegate { get; set; }

    [Export ("cardInformation", ArgumentSemantic.Retain)]
    MITCardInformation CardInformation { get; set; }

    [Export ("url")]
    string Url { set; }

    [Export ("deviceConnect")]
    bool DeviceConnect { get; }

    [Export ("deviceDissconnect")]
    void DeviceDissconnect ();

    [Export ("getConnectionID")]
    string GetConnectionID { get; }

    [Export ("getName")]
    string GetName { get; }

    [Export ("getManufacturer")]
    string GetManufacturer { get; }

    [Export ("getModelNumber")]
    string GetModelNumber { get; }

    [Export ("getSerialNumber")]
    string GetSerialNumber { get; }

    [Export ("getFirmwareRevision")]
    string GetFirmwareRevision { get; }

    [Export ("getHardwareRevision")]
    string GetHardwareRevision { get; }

    [Export ("getTransactionsWithUser:password:")]
    void getTransactionsWithUser (string user, string password);

    [Export ("sndEmvDirectSellWithAmount:company:branch:user:password:usrTrx:merchant:reference:operationType:country:currency:amexCvv:")]
    void SndEmvDirectSellWithAmount (string amount, string company, string branch, string user, string password, string usrTrx, string merchant, string reference, string operationType, string country, string currency, string amexCvv);

    [Export ("sndMsrDirectSellWithAmount:company:branch:user:password:usrTrx:merchant:reference:operationType:country:currency:amexCvv:")]
    void SndMsrDirectSellWithAmount (string amount, string company, string branch, string user, string password, string usrTrx, string merchant, string reference, string operationType, string country, string currency, string amexCvv);


    [Export ("sndReprintVoucherWithUser:password:company:branch:folio:")]
    void SndReprintVoucherWithUser (string user, string password, string company, string branch, string folio);

    [Export ("sndCancelTransacctionWithUser:password:company:branch:folio:auth:amount:")]
    void SndCancelTransacctionWithUser (string user, string password, string company, string branch, string folio, string auth, string amount);


    [Export ("sndPay:")]
    void SndPay (string merchant);

    [Export ("sndEmailWithAddress:copyAddress:folio:User:password:company:branch:")]
    void SndEmailWithAddress (string address, string copyAddress, string folio, string user, string password, string company, string branch);

    [ExportAttribute("sndTaeServiceEmailWithAddress:copyAddress:folio:user:password:company:branch:idTaeCategory:idTaeProvider:idTaeProduct:")]
    void SndTaeServiceEmailWithAddress (string address, string copyAddress, string folio, string user, string password, string company, string branch, string idTaeCategory, string idTaeProvider, string idTaeProduct);

    [Export ("sndSmsWithCellPhoneNumber:carrier:folio:company:branch:User:password:")]
    void sndSmsWithCellPhoneNumber (string cellPhoneNumber, string carrier, string folio, string company, string branch, string user, string password);

    [Export ("uploadSignatureWithImage:folio:")]
    void UploadSignatureWithImage (UIView view, string folio);

    [Export ("device")]
    nint Device { set; }

    [Export ("monthsToPay")]
    string MonthsToPay { set; }

    [Export ("sndElectronicBillWithUser:company:branch:amount:ticket:folio:concept:ccNumber:billType:emailAddress:")]
    void SndElectronicBillWithUser(string user, string company,string branch,string amount,string ticket,string folio,string concept,string ccNumber,string billType,string emailAddress);

    [Export ("cancelWalkerReader")]
    void CancelWalkerReader ();

    [Export ("cancelWalkerTransaction")]
    void CancelWalkerTransaction ();

    [Export ("getWalkerUid")]
    void GetWalkerUid ();

    [Export ("getWalkerBatteryLevel")]
    void GetWalkerBatteryLevel ();
}

Answer 1

Don't add the fake parameter, that's the wrong solution for the problem you're trying to solve.

Unfortunately you we don't support the C#-event-pattern with Objective-C delegates that don't take any parameters [1].

The solution is to use the Objective-C delegate pattern instead.

In the API definition define the class like this:

[BaseType (typeof (NSObject),Name = "MITIntegration"]
public partial interface MITIntegration {
    [Export ("delegate", ArgumentSemantic.Assign), NullAllowed]
    MITIntegrationDelegate Delegate { get; set; }

    // ...
}

and then use it like this:

class MyClass {
    MITIntegration integration;
    MyIntegrationDelegate integration_delegate;
    void Initialize ()
    {
        integration = new MITIntegration ();
        integration.Delegate = integration_delegate; 
    }
}

class MyIntegrationDelegate : MITIntegrationDelegate {
    public override void DidFinishSendMail ()
    {
        // handle this somehow
    }
}

[1] The Objective-C guidelines say that the first argument should be the object that sends the message.