React-Native fetch, Network request failed. not using localhost

You should check out this link: https://github.com/facebook/react-native/issues/8118

Looks like the issue emerged in React Native 0.28. Solution is to "Allow Arbitrary Loads" in the info.plist file found in the ios>build folder that React creates.

If you open the entire ios folder in xcode, then open this info.plist file you can create a new key to Allow Arbitrary Loads and it should fix your issue.