How to Set Initial Values for Nsuserdefault Keys

How to set initial values for NSUserDefault Keys?

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.

NSUserDefaults - how to set start value?

You can set initial values using registerDefaults: which takes an NSDictionary of all your initial keys and their respective values. Example:

[[NSUserDefaults standardUserDefaults] registerDefaults:@{ kSoundEnabled : @YES }];

NSUserDefaults: how to get only the keys I've set

Elegant approach

NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSString *bundleIdentifier = [[NSBundle mainBundle] bundleIdentifier];
NSDictionary *dict = [defaults persistentDomainForName:bundleIdentifier];

File approach:

NSString *bundleIdentifier = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleIdentifier"];
NSString *path = [NSString stringWithFormat:@"~/Library/Preferences/%@.plist",bundleIdentifier];
NSDictionary *dict = [NSDictionary dictionaryWithContentsOfFile:[path stringByExpandingTildeInPath]];
NSArray *keys = [dict allKeys];

Tested with sandboxing.

NSUserDefaults key initialization when app starts for the first time

Try this,

let defaults = NSUserDefaults.standardUserDefaults()
if (defaults.objectForKey("fasterDemo")) {//no need to use '==nil'
    defaults.setBool(true, forKey: "fasterDemo")
}

and,

let demo = defaults.boolForKey("fasterDemo")
var timerSpeed: Double = 1

if (demo) {//same as 'demo == true'
    timerSpeed = 0.001
}
else {
    timerSpeed = 1
}

timer = NSTimer.scheduledTimerWithTimeInterval(timerSpeed, target: self, selector: Selector("countdownTimer"), userInfo: nil, repeats: true)

Note the stringForKey has been replaced with boolForKey

NSUserDefaults set the default value of integer variable to empty

Well, this line:

 int port = [defaults integerForKey:@"port"];

will always assign some value to port.

Also, this:

 NSString *portString = [NSString stringWithFormat:@"%lu",(unsigned long)port];

will always produce a non-empty string. There's no value you could pass for a %lu specifier that will produce an empty string.

So, what you want to do is ask for the object that's stored in the preferences, without converting it to a integer value:

id portObject = [defaults objectForKey:@"port"];
if (portObject)
{
    NSInteger port;
    if ([portObject respondsToSelector:@selector(integerValue)])
        port = [portObject integerValue];
    else
    {
        // portObject is some unexpected class of object, such as an array or dictionary. Take some appropriate action. Or:
        port = 0;
    }
    portField.text = [NSString stringWithFormat:@"%ld", (long)port];
}
else
{
    // There was no value either stored or registered for the key "port"
    portField.text = @"";
}

Note that for this to work, you must not have registered a default value for the "port" key using -[NSUserDefaults registerDefaults:].

Setting default settings in NSUserDefaults. What I do wrong?

You forgot to write this after to change something in NSUserDefaults

[defaults synchronize];

How to deal with non-optional values in NSUserDefaults in Swift

Register the user defaults in AppDelegate, the best place is awakeFromNib or even init. You can provide custom default values for every key.

 override init()
 {
   let defaults = UserDefaults.standard
   let defaultValues = ["key1" : 12, "key2" : 12.6]
   defaults.register(defaults: defaultValues)
   super.init()
 }

Then you can read the values from everywhere always as non-optionals

let defaults = UserDefaults.standard
myVariable1 = defaults.integer(forKey: "key1")
myVariable2 = defaults.double(forKey:"key2")

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