Apply #259

lib/permissions.ios.js

 
 class ReactNativePermissions {
   canOpenSettings: () => Promise<boolean> = () =>
-    PermissionsIOS.canOpenSettings();
+    PermissionsIOS.canOpenSettings().then(result => !!result);
 
   openSettings: () => Promise<*> = () => PermissionsIOS.openSettings();