Question: I have a problem with CATextLayer cleaning.
and with iOS the solution is:

```
textLayer.contentsScale = UIScreen.mainScreen.scale

```

But I can't found "scale" property on cocoa NSScreen

Note: Answer with Object-C or Swift are OK.

Answer: 
`[[NSScreen mainScreen] backingScaleFactor]` will give you the scaling factor for main display
swift 4.2:

```
(NSScreen.main?.backingScaleFactor)!

```