How to set initial values for NSUserDefault Keys?

问题:

I want to set some initial values for my NSUserDefault keys so that the first run of the app has some reasonable initial settings. I thought I ran across a simple way to do this in the app bundle .plist, but now I can't find it. Any ideas?

回答1:

You should use the registerDefaults method of NSUserDefaults. Prepare a plist file in your bundle that contains the default preferences and then use that plist to register the defaults.

NSString *defaultPrefsFile = [[NSBundle mainBundle] pathForResource:@"defaultPrefs" ofType:@"plist"];
NSDictionary *defaultPreferences = [NSDictionary dictionaryWithContentsOfFile:defaultPrefsFile];
[[NSUserDefaults standardUserDefaults] registerDefaults:defaultPreferences];

You have to execute this code on every launch of your app. It will add these values to a separate domain in the user defaults hierarchy. Whenever your app's user defaults don't provide a value for a certain key, NSUserDefaults will fall back to this domain and retrieve the value from there.

回答2:

If you have many default values, let use ola's answer, otherwise this is good for a few params

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

if (![defaults boolForKey:USERDEFAULT_IS_INITIALIZED]) { 
    [defaults setBool:YES forKey:USERDEFAULT_IS_INITIALIZED];

    // Set initial values 
    ...

    [defaults synchronize];
}

回答3:

if ([[[[NSUserDefaults standardUserDefaults] dictionaryRepresentation] allKeys] containsObject:@"initialValuesHaveBeenWritten"])
{
    [[NSUserDefaults standardUserDefaults] setValue:obj1 forKey:key1];
    [[NSUserDefaults standardUserDefaults] setValue:obj2 forKey:key2];


    [[NSUserDefaults standardUserDefaults] setValue:obj1 forKey:@"initialValuesHaveBeenWritten"];

    [[NSUserDefaults standardUserDefaults] synchronize];
}

NB: Not tested, done from memory

回答4:

-(void) loadDef
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

    _removeAd=[userDefaults boolForKey:SAVE_AD_STATUS];

    NSString* strDefSetting=[userDefaults stringForKey:SAVE_STATUS_ADSETTING];
    if(strDefSetting==nil
       ||[strDefSetting isEqualToString:@""]
       )
    {
        strDefSetting=@"0.5";
    }

    _floatAdmob=strDefSetting.floatValue;//0.5;
}