Objective-c – Should I use NSUserDefaults or a plist to store data

cocoa-touchiphonensuserdefaultsobjective cplist

I will be storing a few strings (maybe 10-20). I am not sure if I should use NSUserDefaults to save them, or write them out to a plist. What is considered best practice? NSUserDefaults seems like it is less lines of code, therefore quicker to implement.

I'd like to add that these string values will be added/removed by the user.

Best Answer

I am assuming an array, but it will work with dictionaries too.

Userdefaults, Core Data and Plists can all be read/write but if you use a plist you need to pay attention in what dir you put it. See the plist part down below.

Core Data I think it's way too much overkill, it's just strings. It's supposed to be used when you want to persist more complex objects.

NSUserDefaults:

It's pretty fast and easy to do, though it's supposed to store only user settings. To write them to the userdefaults:

NSArray *stringsArray = [[NSArray alloc] arrayWithObjects: string1, string2, string3, nil];
[[NSUserDefaults standardUserDefaults] setObject:stringsArray forKey:@"MyStrings"];
[[NSUserDefaults standardUserDefaults] synchronize];

To read the from the userdefaults:

NSArray *stringsArray = [[NSUserDefaults standardUserDefaults] objectForKey:@"MyStrings"];

Plist:

If your strings are going to be modified you will need to write and read a plist but you cant't write into your app's resources.

To have a read/write plist first find the documents directory

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *stringsPlistPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Strings.plist"];

Create the array (I am assuming the strings are string1, ...)

NSArray *stringsArray = [[NSArray alloc] arrayWithObjects: string1, string2, string3, nil];

Write it to file

[stringsArray writeToFile:stringsPlistPath atomically:YES];

To read the plist:

Find the documents directory

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *stringsPlistPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Strings.plist"];

Read it in:

NSArray *stringsArray = [NSArray arrayWithContentsOfFile:stringsPlistPath];

Related Solutions

Ios – Clearing NSUserDefaults

You can remove the application's persistent domain like this:

NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];
[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];

In Swift 3 and later:

if let bundleID = Bundle.main.bundleIdentifier {
    UserDefaults.standard.removePersistentDomain(forName: bundleID)
}

This is similar to the answer by @samvermette but is a little bit cleaner IMO.

Ios – How to store custom objects in NSUserDefaults

On your Player class, implement the following two methods (substituting calls to encodeObject with something relevant to your own object):

- (void)encodeWithCoder:(NSCoder *)encoder {
    //Encode properties, other class variables, etc
    [encoder encodeObject:self.question forKey:@"question"];
    [encoder encodeObject:self.categoryName forKey:@"category"];
    [encoder encodeObject:self.subCategoryName forKey:@"subcategory"];
}

- (id)initWithCoder:(NSCoder *)decoder {
    if((self = [super init])) {
        //decode properties, other class vars
        self.question = [decoder decodeObjectForKey:@"question"];
        self.categoryName = [decoder decodeObjectForKey:@"category"];
        self.subCategoryName = [decoder decodeObjectForKey:@"subcategory"];
    }
    return self;
}

Reading and writing from NSUserDefaults:

- (void)saveCustomObject:(MyObject *)object key:(NSString *)key {
    NSData *encodedObject = [NSKeyedArchiver archivedDataWithRootObject:object];
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:encodedObject forKey:key];
    [defaults synchronize];

}

- (MyObject *)loadCustomObjectWithKey:(NSString *)key {
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSData *encodedObject = [defaults objectForKey:key];
    MyObject *object = [NSKeyedUnarchiver unarchiveObjectWithData:encodedObject];
    return object;
}

Code shamelessly borrowed from: saving class in nsuserdefaults

Best Answer

Related Solutions

Ios – Clearing NSUserDefaults

Ios – How to store custom objects in NSUserDefaults

Related Topic