Should I use NSUserDefaults or a plist to store da

Question

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.

Answer 1

If you are storing 10-20 strings and are looking for not too many lines of code, core data is certainly much too much overhead. I recommend going with the plist. Not a lot of code:

NSURL *plistURL = [[NSBundle mainBundle] URLForResource:@"MyStrings" withExtension:@"plist"];
NSArray *stringArray = [NSArray arrayWithContentsOfURL:plistURL];

Answer 2

It depends on what you want to store and why. NSUserDefaults is meant for storing user preferences. You can try to use it for other things, but you probably shouldn't.

Otherwise, if your needs are simple a plist file is pretty straightforward. You can also use core data or come up with your own file format. In general, I use plist for simple tasks and then move to core data for anything more complex.

Answer 3

NSUSerDefaults is indeed quick to implement, but mostly as your application grows, you want to store more and more, I went directly for plist files.

Mostly, people want to store a list of something, so here is my share on how to do this with NSDictionary. This does not require you to create a plist file first, it will be created at the first time saving something

xcode 7 beta, Swift 2.0

saving

func SaveItemFavorites(items : Array<ItemFavorite>) -> Bool
{
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) as NSArray
    let docuDir = paths.firstObject as! String
    let path = docuDir.stringByAppendingPathComponent(ItemFavoritesFilePath)
    let filemanager = NSFileManager.defaultManager()

    let array = NSMutableArray()        

    for var i = 0 ; i < items.count ; i++
    {
        let dict = NSMutableDictionary()
        let ItemCode = items[i].ItemCode as NSString

        dict.setObject(ItemCode, forKey: "ItemCode")
        //add any aditional..
        array[i] = dict
    }

    let favoritesDictionary = NSDictionary(object: array, forKey: "favorites")
    //check if file exists
    if(!filemanager.fileExistsAtPath(path))
    {
        let created = filemanager.createFileAtPath(path, contents: nil, attributes: nil)
         if(created)
         {
             let succeeded = favoritesDictionary.writeToFile(path, atomically: true)
             return succeeded
         }
         return false
    }
    else
    {
        let succeeded = notificationDictionary.writeToFile(path, atomically: true)
        return succeeded
    }
}

Little note from the docs:

NSDictionary.writeToFile(path:atomically:)

This method recursively validates that all the contained objects are property list objects (instances of NSData, NSDate, NSNumber, NSString, NSArray, or NSDictionary) before writing out the file, and returns NO if all the objects are not property list objects, since the resultant file would not be a valid property list.

So whatever you set at dict.SetObject() should be one of the above mentioned types.

loading

private let ItemFavoritesFilePath = "ItemFavorites.plist"

func LoadItemFavorites() -> Array<ItemFavorite>
{
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) as NSArray
    let docuDir = paths.firstObject as! String
    let path = docuDir.stringByAppendingPathComponent(ItemFavoritesFilePath)
    let dict = NSDictionary(contentsOfFile: path)
    let dictitems : AnyObject? = dict?.objectForKey("favorites")

    var favoriteItemsList = Array<ItemFavorite>()

    if let arrayitems = dictitems as? NSArray
    {
        for var i = 0;i<arrayitems.count;i++
        {
            if let itemDict = arrayitems[i] as? NSDictionary
            {
                let ItemCode = itemDict.objectForKey("ItemCode") as? String
                //get any additional

                let ItemFavorite = ItemFavorite(item: ItemCode)
                favoriteItemsList.append(ItemFavorite)
            }
        }
    }

    return favoriteItemsList
}