a #GType supporting #GAsyncInitable.
the name of the first property, followed by the value, and other property value pairs, and ended by %NULL.
The var args list generated from @first_property_name.
the [I/O priority][io-priority] of the operation
optional #GCancellable object, %NULL to ignore.
a #GAsyncReadyCallback to call when the initialization is finished
the data to pass to callback function
2.22
Helper function for constructing #GAsyncInitable object. This is similar to g_object_new_valist() but also initializes the object asynchronously.
When the initialization is finished, @callback will be called. You can then call g_async_initable_new_finish() to get the new object and check for any errors.