Please explain NSUserDefault purpose - iphone

Question

NSUserDefaults *nsu=[NSUserDefaults standardUserDefaults];
[nsu setObject:[postdata objectForKey:#"url"] forKey:#"url"];
Can anyone explain purpose of NSUserDefault?

Answer 1

I think it is worth mentioning that NSUserDefaults can and should be used to store small amounts of data dealing with user settings and app configuration not set in the Settings.bundle. It is not recommended storing anything with sensitive user information (username, password, etc) as these values are saved in a plain text .plist file in the documents directory.
User defaults can be very flexible and the sky is the limit as to its use, but care should be taken to protect the user's private data. For login information, use the built in keychain. For everything else, there are plenty of options. (e.g. CoreDate, Sqlite)

Answer 2

I hope this is help u.....
NSUserDefaults is a quick and easy way to store small amounts of data for you app. In this example, I’m going to show you how to use NSUserDefaults to store and retrieve data.
Storing Data
// create a standardUserDefaults variable
NSUserDefaults * standardUserDefaults = [NSUserDefaults standardUserDefaults];
// saving an NSString
[standardUserDefaults setObject:#"mystring" forKey:#"string"];
// saving an NSInteger
[standardUserDefaults setInteger:42 forKey:#"integer"];
// saving a Double
[standardUserDefaults setDouble:3.1415 forKey:#"double"];
// saving a Float
[standardUserDefaults setFloat:3.1415 forKey:#"float"];
// synchronize the settings
[standardUserDefaults synchronize];
Retrieving Data
// create a standardUserDefaults variable
NSUserDefaults *standardUserDefaults = [NSUserDefaults standardUserDefaults];
// getting an NSString object
NSString *myString = [standardUserDefaults stringForKey:#"keyToLookupString"];
// getting an NSInteger object
NSInteger myInt = [standardUserDefaults integerForKey:#"integerKey"];
// getting an Float object
float myFloat = [standardUserDefaults floatForKey:#"floatKey"];
Try this Example also
http://mobile.tutsplus.com/tutorials/iphone/nsuserdefaults_iphone-sdk/

Answer 3

If you want to store data like user_id, name, etc., for your application, which can be accessible anywhere throughout your application, then NSUserDefaults can be used. It is like storing data in user preferences.
For more details, see
NSUserDefaults

Answer 4

NSUserDefault is generally used for storing data for an app in a global manner within the app. When you store a value in NSUserDefault it will be available until the app is removed from the device. In your above example, you store url in key url. You can access the value from anywhere using:
NSUserDefaults *nsu=[NSUserDefaults standardUserDefaults];
NSString *url = [nsu ObjectforKey:#"url"];

Answer 5

NSUserDefault is used to save small amount of data in your App. If your application needs to store certain data which is small in size, so to better avoid concepts like SQLite we use NSUserDefault. I suggest you to go through the following link for better understanding.
Click here for Tutorial