iOS Swift CoreMedia CMFormatDescriptionRef链接器错误

Question

I'm trying to read a format descriptor from one of my AVAssetTrack's with the following code:

var audioTrack:AVAssetTrack = self.asset!.tracksWithMediaType(AVMediaTypeAudio)[0] as AVAssetTrack
var formatDescription:CMFormatDescriptionRef = audioTrack.formatDescriptions[0] as CMFormatDescriptionRef

The problem is the downcast "as CMFormatDescriptionRef". I can declare a variable with type CMFormatDescriptionRef just fine but with the downcast I'm getting a linker error despite having added the CoreMedia framework and an "import CoreMedia" in my swift file. This is the linker error I get:

Undefined symbols for architecture armv7:
  "_OBJC_CLASS_$_CMFormatDescription", referenced from:

Any help would be appreciated.

Answer 1

您需要将您的项目与CoreMedia.framwork链接。