set event tracker in iOOS example app (#1630)
set event tracker in iOOS example app (#1630)

Signed-off-by: Rafal Augustyniak <c112854348d0b65cbb3818b4bb8eb5588417f7f1@lyft.com>
envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile,envoyproxy/envoy-mobile