Question: how to transfer data from nike+ to strava?
Answer: You open it, add your Nike and Strava accounts (and Apple Health if you wish) – click 3 bars on left, Accounts & Settings then tap the account you want to connect. ... 
Then you can sync your data to the app.
Then you can export your data to Strava – or whichever app you want.
There are 2 choices for doing this.