Xamarin iOS binding with Swift framework fails on build

Question

Xamarin iOS binding with Swift framework fails on build

Luc MOUSSIEGT 1

I encounter a problem building a Xamarin.iOS Binding library project.

So for context, I have to integrate a Swift framework (built with SDK iphoneos14.5) into a Xamarin project. The framework was delivered with Objective-C headers containing the required interface members, so I was able to use Objective Sharpie to generate the ApiDefinitions.cs and StructsAndEnums.cs files using the following command line:

sharpie bind -sdk iphoneos15.0 -scope MyFramework.framework/Headers/ -c -F. MyFramework.framework/Headers/MyFramework.h

Now, I added the generated files in a new Xamarin.iOS Bindings solution. I added the framework MyFramework.framework as native reference to the project, changed native reference properties to enable "Smart Link", disable "Force Load", and add UIKit and Foundation to the Frameworks entry.

The issue I'm facing is with some class types that were referenced as forward declarations (@class declaration) in the headers of the framework, and that were ignored by Objective Sharpie. I suppose they are in the native library, but the line

using MyFramework;

fails and outputs CS0246: type or namespace not found.

How am I supposed to solve this ? Should I create empty declarations for the missing types? Am i writing this using wrong?

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-01-12T08:48:51.34+00:00

I'm not sure if the namespace of ApiDefinitions.cs and StructsAndEnums.cs is MyFramework or not, you could check it. I follow this walkthrough and download the demo to test. When I run the project via VS2019, it works fine. Would you mind sharing the VS version ?
Luc MOUSSIEGT 1 Reputation point

2022-01-12T11:12:46.57+00:00

I'm using VS 2019 for Mac. Objective Sharpie actually added that using MyFramework;, I don't think it has anything to do with the namespace of the files (which I chose myself in accordance with my company's naming rules).
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-01-13T01:35:45.067+00:00

Hi @Luc MOUSSIEGT . According to the walkthrough, when you Build a binding library , the namespace of ApiDefinitions.cs and StructsAndEnums.cs need be same as your Xamarin.iOS binding library project in the Step3.

*Copy metadata generated by Sharpie at one of the previous steps, select the following Build Action in the properties window: ObjBindingApiDefinition for the ApiDefinitions.cs file and ObjBindingCoreSource for the StructsAndEnums.cs file*

You could right click the Xamarin.iOS binding library project, go to Main Settings, it's suggested to use the same title of Name and Default Namespace.

I'm afraid type or namespace not found error occurs at ** Consume the binding library ** step, you could check the namespace in the above step. Then remove the reference to the binding library and add again.

If you have any other issues, feel free to let me know.
Luc MOUSSIEGT 1 Reputation point

2022-01-13T11:08:07.09+00:00

The type or namespace not found error does not occur at the "Consumethe binding library" step, it occurs as I try to build the binding project.

I have tried what you suggested, i.e. changing the default namespace of the project to the actual namespace used in the ApiDefinitions.cs file, but to no avail. I think some declarations are simply missing from the public header files of the framework. I don't know if Objective Sharpie is supposed to find the non-public declarations as well, but it did not work in my case.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-02-09T02:20:23.82+00:00

Sorry for my late reply. Best way to investigate this is to get a sample project that shows the issue and includes the framework you want to bind. Would you mind sharing a demo with me? You could upload it to github and attacth the link here.
But initially, the @class declarations would be ignored by objective sharpie, but when the class declared with @class is actually in the headers, then objective sharpie should generate bindings for it. If the types are private, bindings will not be generated.
Some libraries are not well formed, and this may be one of them. As such, some manual editing of the ApiDefinitions may be required. If you do not need direct access to the missing types, you can edit the ApiDefinitions to use NSObject in place of any of the missing types as a possible workaround.

Your answer

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-01-12T08:48:51.34+00:00

I'm not sure if the namespace of ApiDefinitions.cs and StructsAndEnums.cs is MyFramework or not, you could check it. I follow this walkthrough and download the demo to test. When I run the project via VS2019, it works fine. Would you mind sharing the VS version ?
Luc MOUSSIEGT 1 Reputation point

2022-01-12T11:12:46.57+00:00

I'm using VS 2019 for Mac. Objective Sharpie actually added that using MyFramework;, I don't think it has anything to do with the namespace of the files (which I chose myself in accordance with my company's naming rules).
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-01-13T01:35:45.067+00:00

Hi @Luc MOUSSIEGT . According to the walkthrough, when you Build a binding library , the namespace of ApiDefinitions.cs and StructsAndEnums.cs need be same as your Xamarin.iOS binding library project in the Step3.

*Copy metadata generated by Sharpie at one of the previous steps, select the following Build Action in the properties window: ObjBindingApiDefinition for the ApiDefinitions.cs file and ObjBindingCoreSource for the StructsAndEnums.cs file*

You could right click the Xamarin.iOS binding library project, go to Main Settings, it's suggested to use the same title of Name and Default Namespace.

I'm afraid type or namespace not found error occurs at ** Consume the binding library ** step, you could check the namespace in the above step. Then remove the reference to the binding library and add again.

If you have any other issues, feel free to let me know.
Luc MOUSSIEGT 1 Reputation point

2022-01-13T11:08:07.09+00:00

The type or namespace not found error does not occur at the "Consumethe binding library" step, it occurs as I try to build the binding project.

I have tried what you suggested, i.e. changing the default namespace of the project to the actual namespace used in the ApiDefinitions.cs file, but to no avail. I think some declarations are simply missing from the public header files of the framework. I don't know if Objective Sharpie is supposed to find the non-public declarations as well, but it did not work in my case.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-02-09T02:20:23.82+00:00

Sorry for my late reply. Best way to investigate this is to get a sample project that shows the issue and includes the framework you want to bind. Would you mind sharing a demo with me? You could upload it to github and attacth the link here.
But initially, the @class declarations would be ignored by objective sharpie, but when the class declared with @class is actually in the headers, then objective sharpie should generate bindings for it. If the types are private, bindings will not be generated.
Some libraries are not well formed, and this may be one of them. As such, some manual editing of the ApiDefinitions may be required. If you do not need direct access to the missing types, you can edit the ApiDefinitions to use NSObject in place of any of the missing types as a possible workaround.

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Xamarin iOS binding with Swift framework fails on build

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