currentPassDescription
An object that describes the requirements for the current pass.
Declaration
var currentPassDescription: AVAssetWriterInputPassDescription? { get }Discussion
If the value of this property is nil, call the asset writer input’s markAsFinished() method because there are no more requests to fulfill.
During the first pass, the request contains a single time range value, from zero to positive infinity, that indicates to append all media from the source. This condition is also true when canPerformMultiplePasses is false, in which case the asset writer only performs a single pass.
The value of this property is nil before you call startWriting() on the containing asset writer. It transitions to an initial non-nil value during the call to startWriting(), and changes only after a call to markCurrentPassAsFinished(). You can use the respondToEachPassDescription(on:using:) to have the system call you at the beginning of each pass.
This property is key-value observable. The system doesn’t notify an observer on a specific thread.