After some research, I eventually found the answer here
Before seeing this page, I knew that I should use AddSecurityRequirement
after AddSecurityDefinition
because of many samples, but it was a problem that the function parameters have changed on .NET Core 3.0.
By the way, the final answer is as below:
services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1", new OpenApiInfo {
Title = "My API",
Version = "v1"
});
c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme {
In = ParameterLocation.Header,
Description = "Please insert JWT with Bearer into field",
Name = "Authorization",
Type = SecuritySchemeType.ApiKey
});
c.AddSecurityRequirement(new OpenApiSecurityRequirement {
{
new OpenApiSecurityScheme
{
Reference = new OpenApiReference
{
Type = ReferenceType.SecurityScheme,
Id = "Bearer"
}
},
new string[] { }
}
});
});