我正在使用AVAssetWriter和AVCaptureVideoDataOutput进行实时视频录制。我在用户设备上看到许多崩溃报告,但是无法在我的任何设备上重现它。我需要以下代码中可能出错的信息。发生这种情况的原因可能是NSDictionary对[String:AnyObject]的类型转换失败。
在课堂上,我有:
private var videoOut: AVCaptureVideoDataOutput?
然后在函数中,我这样做:
var recommendedSettings:[String:AnyObject]?
recommendedSettings = videoOut.recommendedVideoSettings(forVideoCodecType: AVVideoCodecType.hevc, assetWriterOutputFileType: AVFileType.mov) as? [String : AnyObject]
if let recommendedSettings = recommendedSettings {
/* crashes here */
var compressionSettings = recommendedSettings[AVVideoCompressionPropertiesKey] as! [String:AnyObject]
}
[在Swift中,AVVideoCompressionPropertiesKey返回的字典的假定返回类型是什么?
返回的类型是字典,即
let videoCompressionProps: Dictionary<String, Any> = [
AVVideoAverageBitRateKey : videoBitrate,
AVVideoMaxKeyFrameIntervalKey : videomaxKeyFrameInterval,
AVVideoProfileLevelKey : avVideoProfileLevel
]