ios - Store a value for the app's running time -

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i need store boolean value persist app's running time. when user quit app (from background well) variable should reset default. how can this?

i tried constants. keep constants in separate .h file. in declared this.

const bool hasshowntutorial = no;

and in view controller, 

if (hasshowntutorial == no) {     [self showapptutorial];     hasshowntutorial = yes; }

i error @ hasshowntutorial = yes; saying read-only variable not assignable.

i tried going using nsuserdefaults. thing value stored once set it. there way clear when app quits?

i'd appreciate input , suggestions.

thank you.

store in nsuserdefaults under specific key. 

[[nsuserdefaults standarddefaults] setbool:<mybool> forkey:@"mykey"];

then retrieve later.

bool b = [[nsuserdefaults standarddefaults] boolforkey:@"mykey"];

if want clear data.

nsstring *domain = [[nsbundle mainbundle] bundleidentifier]; [[nsuserdefaults standarduserdefaults] removepersistentdomainforname:domain];

for example, in appdelegate's implementation of -applicationwillterminate:, clear data.

- (void)applicationwillterminate:(uiapplication *)application {     nsstring *domain = [[nsbundle mainbundle] bundleidentifier];     [[nsuserdefaults standarduserdefaults] removepersistentdomainforname:domain]; }

edit: if first method of clearing data not work, can use class method +resetstandarduserdefaults. example following clear current defaults.

[nsuserdefaults resetstandarduserdefaults];

a third possiblity remove property.

[[nsuserdefaults standarduserdefaults] removeobjectforkey:@"mykey"];

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