Added NULL safety checks

These were reported as potential flaws by VeraCode scan.
Fixed potential memory leak
```clean_paths``` is deprecated in CocoaPods. Use preserve_paths instead.
update podspec to version 1.6.2
Merge pull request #103 from nickcheng/patch-1

clean_paths is deprecated in CocoaPods. Use preserve_paths instead...
Merge pull request #100 from lixar/veracode-fixes

Added NULL safety checks