How to maintain Session for iphone

In my Iphone App, User logins with Username and password. At after user logged in, He can access every attribute, features through APIs. But i want to maintain a session. That is, If user doi开发者_JAVA百科ng nothing in app, After getting 30 mins, Session should expire and user must be asked to login with his Username and password.

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I am currently working on something exactly the same.

I do the following scenario for the session validity:

1. By the first incoming request if the Session Token appeared to be invalid I try to re-generate the session key again silently in the background.

2. If procedure #1 did not work for some reasons such as the user changed his password from somewhere else I redirect the user to the log in page again and I alert something like "Your session key has been expired please log in again".

To get more into this I store the Session key in the NSUserDefaults:

 // Saving the Key
 [[NSUserDefaults standardUserDefaults] setValue:@"ABCDEFGHIJK" forKey:@"SessionKey"];

 // Reading the Key
 [[NSUserDefaults standardUserDefaults] stringForKey:@"SessionKey"];

Hope this helps.

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Set previous time mPreviousTime = [NSDate timeIntervalSinceReferenceDate]; on login and appropriate kThresholdHideValue(In seconds) in your case it is 30min(30*60) and you can check whether the time elapsed using below method...

NSTimeInterval timeNow = [NSDate timeIntervalSinceReferenceDate];
if( ( mPreviousTime + kThresholdHideValue <= timeNow ) )
{
         //Log out
}

And also call mPreviousTime = [NSDate timeIntervalSinceReferenceDate]; when user performs some action. so you can log out only if user does not perform any action for 30min.