xcode - Save Global variable or a php like session -

i'm working on app need help. need 'php-like session' in objective c (without using connection internet) i've thought global vars, app seems reset them when reloading view. current code

secondviewcontroller.h

@interface secondviewcontroller : uiviewcontroller {     nsstring * string; } 

secondviewcontroller.m

@interface secondviewcontroller ()  @end  @implementation secondviewcontroller  - (void)viewdidload {     [super viewdidload];      if (! [string isequaltostring:@"hello"])     {         nslog(@"hello");         string = @"hello";     }     else     {         nslog(@"bye");     } }  @end 

but everytime reload secondviewcontroller 'string' reseted default value. i'm looking use in php (a.e. $_session['string'] = 'hello')

it helpful . stores values until unless delete app device .

nsuserdefaults *prefs = [nsuserdefaults standarduserdefaults];  // saving nsstring [prefs setobject:@"texttosave" forkey:@"keytolookupstring"];  // saving nsinteger [prefs setinteger:42 forkey:@"integerkey"];  // saving double [prefs setdouble:3.1415 forkey:@"doublekey"];  // saving float [prefs setfloat:1.2345678 forkey:@"floatkey"];  // suggested synch prefs, not needed (i didn't put in tut) [prefs synchronize];  **retrieving**  nsuserdefaults *prefs = [nsuserdefaults standarduserdefaults];  // getting nsstring nsstring *mystring = [prefs stringforkey:@"keytolookupstring"];  // getting nsinteger nsinteger myint = [prefs integerforkey:@"integerkey"];  // getting float float myfloat = [prefs floatforkey:@"floatkey"];