pre-start iOS sim

.travis.yml

     - $YARN_CACHE
     - $HOME/.m2
 
+before_install:
+  - export IOS_SIMULATOR_UDID=`instruments -s devices | grep "iPhone 7" | awk -F '[ ]' '{print $4}' | awk -F '[\[]' '{print $2}' | sed 's/.$//'`
+  - echo $IOS_SIMULATOR_UDID
+  - open -a "simulator" --args -CurrentDeviceUDID $IOS_SIMULATOR_UDID
+
 install:
   # node
   - curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.1/install.sh | bash