SwaggerUI with .NetCore 3.0 bearer token authorization

There are two points in your code:

1. For OpenApiSecurityRequirement in OpenApiSecurityRequirement, need to set OpenApiReference
2. Need to specify Scheme with bearer

Here is a working demo:

services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo
    {
        Version = "v1",
        Title = "API",
        Description = "QPIN API with ASP.NET Core 3.0",
        Contact = new OpenApiContact()
        {
            Name = "Tafsir Dadeh Zarrin",
            Url = new Uri("http://www.tdz.co.ir")
        }
    });
    var securitySchema = new OpenApiSecurityScheme
    {
        Description = "JWT Authorization header using the Bearer scheme. Example: \"Authorization: Bearer {token}\"",
        Name = "Authorization",
        In = ParameterLocation.Header,
        Type = SecuritySchemeType.Http,
        Scheme = "bearer",
        Reference = new OpenApiReference
        {
            Type = ReferenceType.SecurityScheme,
            Id = "Bearer"
        }
    };
    c.AddSecurityDefinition("Bearer", securitySchema);

    var securityRequirement = new OpenApiSecurityRequirement();
    securityRequirement.Add(securitySchema, new[] { "Bearer" });
    c.AddSecurityRequirement(securityRequirement);
});

My implementation - excludes locks on non protected endpoints - with OperationFilter

internal static void SwaggerSetup(this IServiceCollection services, OpenApiInfo settings)
    {
        if (settings.Version != null)
        {
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc(settings.Version, settings);
                c.OperationFilter<AddAuthHeaderOperationFilter>();
                c.AddSecurityDefinition("bearer", new OpenApiSecurityScheme
                {
                    Description = "`Token only!!!` - without `Bearer_` prefix",
                    Type = SecuritySchemeType.Http,
                    BearerFormat = "JWT",
                    In = ParameterLocation.Header,
                    Scheme = "bearer"
                });
            });
        }
    }

and the OperationFilter

private class AddAuthHeaderOperationFilter : IOperationFilter
    {
        public void Apply(OpenApiOperation operation, OperationFilterContext context)
        {
            var isAuthorized = (context.MethodInfo.DeclaringType.GetCustomAttributes(true).OfType<AuthorizeAttribute>().Any()
                                && !context.MethodInfo.DeclaringType.GetCustomAttributes(true).OfType<AllowAnonymousAttribute>().Any()) //this excludes controllers with AllowAnonymous attribute in case base controller has Authorize attribute
                                || (context.MethodInfo.GetCustomAttributes(true).OfType<AuthorizeAttribute>().Any()
                                && !context.MethodInfo.GetCustomAttributes(true).OfType<AllowAnonymousAttribute>().Any()); // this excludes methods with AllowAnonymous attribute

            if (!isAuthorized) return;

            operation.Responses.TryAdd("401", new OpenApiResponse { Description = "Unauthorized" });
            operation.Responses.TryAdd("403", new OpenApiResponse { Description = "Forbidden" });

            var jwtbearerScheme = new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference { Type = ReferenceType.SecurityScheme, Id = "bearer" }
            };

            operation.Security = new List<OpenApiSecurityRequirement>
            {
                new OpenApiSecurityRequirement { [jwtbearerScheme] = new string []{} }
            };
        }
    }

Reference https://thecodebuzz.com/jwt-authorize-swagger-using-ioperationfilter-asp-net-core/

just added the condition to exclude AllowAnonymous decorated methods