Steve

the default vlue of textContainerInset is (8, 0, 8, 0) For example: ``` UIEdgeInsets edgeInsets = _textView.internalTextView.textContainerInset; edgeInsets.left = 8; edgeInsets.right = 8; _textView.internalTextView.textContainerInset = edgeInsets; ```

Becase the scale on 6S plus is 3, when the value is 192.5, `CHTFloorCGFloat`return 192.33333333333334，I think you may keep one decimal by set scale to 10. 

Migrated: swift 3.0 → 4.0

1

Ext: add `clearDrawLayer` function in `startScan` function for clearing operation