Get the video thumbnail exception on ios

[bhjSky]

Gets the image as null on thumbnailFile.
The thumbnailFile method does not set the thumbnailPath parameter.
path is nsnull,Is not null

[justsoft]

Thanks for the patch.
@bhjSky Why don't check the thumbnailPath parameter at the first place?

[scofield-hello]

many ios developers have the same problem.

thumbnailFile	String [video], String [thumbnailPath](folder or full path where to store the thumbnail file, null to save to same folder as the video file), ImageFormat imageFormat, int [maxHeight](0: for the original resolution of the video, or scaled by the source aspect ratio), int [maxWidth](0: for the original resolution of the video, or scaled by the source aspect ratio), int [timeMs] generates the thumbnail from the frame around the specified millisecond, int quality	creates a file of the thumbnail from the [video

when set this thumbnailPath as default, it will cause crash.

[justsoft]

Leave the thumbnailPathl as null means the generated thumbnail image into the folder as what the thmbnailFile is.
You have to make sure the folder has the write permissions for this App.