startWriting()
Tells the writer to start writing its output.
Declaration
func startWriting() -> BoolReturn Value
Discussion
You must call this method after you configure the writer and add its inputs to prepare the object to write data. After you call this method, your app can start writing sessions by calling startSession(atSourceTime:) and can write media samples using the methods that the asset writer’s inputs provide.
If writing fails to start, this method returns false. In this case, check the values of the status and error properties to determine the reason for the failure.