CODEWITHSUNDEEP
iphoneobjective-cioscocoa-touch
Jules
Jules

Reputation: 7766

Obj-C, how should I use NSUserDefaults to access settings through-out my app / views, easily / efficiently?

I've been using app delegate interface variables through-out my app to quickly access app wide bits of data.

I believe this is causing efficiency issues in my app. And I've finally decided to move to NSUserDefaults. Unless you suggest some other way ?

Often I will want to access the same variable through-out a view, so it doesn't make sense to access this variable using NSUserDefaults each time. I figure it will be slow.

So I'm thinking a class which will read all the values into an array of some kind, in viewDidLoad and then if a value is altered, save / synchronize and update the class variable.

But if I push to a view, I guess I'm going to have to save then too.

This is beginning to sound a bit messy.

However, I'm just wondering what approach will be efficient and easy to use ?

Upvotes: 0

Views: 321

Answers (3)

hotpaw2
hotpaw2

Reputation: 70703

A shared Model object (using the MVC paradigm) is the usual recommended way to share variables to multiple other objects or classes. This Model object can be a singleton, or other objects can locally copy or be delegated a reference to a single Model object for fast access to its getters/setters.

The fastest variables access method is often just using C global variables (since regular C is a subset of Objective C), if you are willing to deal with potentially more difficult code reuse and debugging problems.

NSUserDefaults is just using the file system as a key-value dictionary global variable. Slow, and with the many of same structure problems as C global variable use.

Upvotes: 1

lorean
lorean

Reputation: 2150

It really depends on the size of data you're accessing. The serialization of several NSDictionary objects to disk may be enough to cause your app to lag.

If you're serious about iOS development, you should learn to use Core Data. Anything NSUserDefaults can do, Core Data does better. The only one advantage NSUserDefaults provides reduces lines of code in tiny one-off apps. Think of Core Data like laying the foundations for a house, and NSUserDefaults like pitching up a tent.

Upvotes: 0

Eugene
Eugene

Reputation: 10045

If you need to use variables like arrays or sets you'd better not use NSUserDefaults since on synchronize they save all stored values onto disk (of course if you don't need storing them to disk). If you need to store large amounts of data in object graphs with relations like this

User
 -name
 -lastname
 -email
 -messages
Message
 -date
 -text

Then you'd better start looking into CoreData framework, it's very easy to use and allows to store large data sets to disk and access them quickly.

If you just need some class that would, for instance, store current user profile values like username, email etc. Try creating a singleton class - which is quite the same as using AppDelegate, but it's much clearer to use when you're separating your data into smaller chunks.

Anyways I wrote this answer based on my assumptions only. It would be nice to know what data kinds you are working with and what is its lifecycle in your app.

Upvotes: 0

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