endSession(atSourceTime:)
Finishes an asset-writing session.
Declaration
func endSession(atSourceTime endTime: CMTime)Parameters
- endTime:
The ending asset time for the session, in the timeline of the source samples.
Discussion
Call this method to complete a session that you started with startSession(atSourceTime:).
The end time defines the moment on the timeline of source samples at which the session ends. In the case of the QuickTime movie file format, each sample-writing session’s start and end time pair corresponds to a period of movie time into which a writer inserts samples. The writer adds samples with timestamps that are later than the session end time to the written file but they aren’t presented during playback. For example, if the first session has duration D1 = endTime - startTime, the writer inserts it into the written file at time 0 through D1; the second session would insert into the written file at time D1 through D1 + D2, and so on. It’s legal to have a session with no samples; this causes the creation of an empty edit of the prescribed duration.
If you don’t explicitly call this method, the system invokes it automatically when you call finishWriting(completionHandler:). In that case, the session’s effective end time is the timestamp of the last sample you append.