Login second time on IOS without showing popup

[binhchili]

I have an app using Facebook account to login. In the first time login IOS device will show a popup to allow my app to login with Facebook. In the second time open app if my app's account isn't logged out in the first time then the app will automatically login without showing popup. This works perfectly on android but not working on IOS. Every time I open the app it keeps showing the popup and it's pretty annoying. Anyone know how to hide the login popup in IOS ?