Update README.md

Author: ivanvorobei

README.md

@@ -130,9 +130,17 @@ alertView.layer.cornerRadius = 40
 
 ### Dark Mode
 
+<img align="left" src="https://github.com/ivanvorobei/SPAlert/blob/master/Resources/Dark-Mode-Preview.jpg" width="250">
+
 The default mode is `Dark Mode`. No additional configuration is required. As soon as the user change the interface to dark, all alerts will appear dark.
 
-<img src="https://github.com/ivanvorobei/SPAlert/blob/master/Resources/Dark-Mode-Preview.jpg" width="250">
+For check state of user appearance I am use `traitCollection`:
+
+```swift
+if self.traitCollection.userInterfaceStyle == .dark { return true }
+```
+
+It available sice iOS 12, for early using always Light Mode. 
 
 ## Required Presets