AVAssetWriter multiple sessions and the status property

问题

I am attempting to create multiple, serial writing sessions with AVAssetWriter. Once I've completed one successfully (after calling finishWriting) the status is set to 2 (AVAssetWriterStatusCompleted).

Trying to create another session, I call startWriting, but I get the error:

[AVAssetWriter startWriting] cannot call method when status is 2

Seems I cannot create a writing session unless I configure something. Do I have to recreate the AVAssetWriter again? I must be missing something, and the docs aren't helping.

Thanks.

回答1:

After the writer has completed it is no longer usable. You must create a new one. From the docs:

You can only use a given instance of AVAssetWriter once to write to a single file. If you want to write to files multiple times, you must use a new instance of AVAssetWriter each time.

I have an app where I use two AVAssetWriters. I create two writers where only one is active at a time. When some time delta is reached I push the active writer onto a GCD queue for completion and recreation, and set the active writer pointer to the other writer.

if(time > delta)
  dispatch( ^{ finish writer, create new one })
  active_writer = next writer

This works well when using a capture queue. You can setup a switch to perform the operations given the state of the writer.

来源：https://stackoverflow.com/questions/4911534/avassetwriter-multiple-sessions-and-the-status-property