How to persist and load an object which conforms to NSCoding protocol?

Question

I have made an class which conforms to the NSCoding protocol and does all the encode and decode stuff.

For my app, I simply want to persist an object from that class to the device and the next time when the app launches, I want to load that object back into memory.

Basically it's just an class which holds some user input information. For example the user starts writing a text but then quits the app. Next time I want to load that data object.

I guess I need NSKeyedArchiver? Is there a good tutorial on this? How do I do that?

score 3 · Accepted Answer · answered Mar 15 '10 at 21:14

3

Yes you need NSKeyed(Un)Archiver. These 2 classes can convert your object to/from NSData which you can save/load it as a file.

To save your object to a file:

if (![NSKeyedArchiver archiveRootObject:your_object toFile:@"filename.plist"])
   // save failed.

To read the object from a file:

id your_object = [NSKeyedUnarchiver unarchiveObjectWithFile:@"filename.plist"];
if (your_object == nil)
  // read failed.

answered Mar 15 '10 at 21:14

kennytm

510,854
105
1,084
1,005

Where is that file stored? In the documents directory? Is this backed up by iTunes automatically? – dontWatchMyProfile Mar 16 '10 at 09:32
@mystify: Anywhere you like (of course you need to supply the full path.) It is backed up if the file is saved to ~/Documents. – kennytm Mar 16 '10 at 11:17

How to persist and load an object which conforms to NSCoding protocol?

1 Answers1