keep code compatible with iOS14

make library iOS15 compatible

revert version-bump

Merge pull request Polidea#381 from Polidea/dev/Version-6.0.0

Version 6.0.0

Merge pull request Polidea#347 from Polidea/Version-5.3.0

Version 5.3.0

Merge pull request Polidea#339 from Polidea/Version-5.2.1

Version 5.2.1

Merge pull request Polidea#331 from Polidea/v5.2.0

Version 5.2.0

version 5.1.4

Merge pull request Polidea#276 from Polidea/v5.1.3

Version 5.1.3

Merge pull request Polidea#269 from Polidea/5.1.2

Version 5.1.2