[iPhone] Property Lists and Key-Valued Coding

1. Docs
2. Summary
   Mac OS X applications use XML propertylists (or plists) for storing things such as your
   default preferences, application settings, and configuration information.
   
3. Read/Write
   
   • If your objects are of type  NSString , NSDictionary , NSArray , NSDate , NSData , or NSNumber , you can use the  writeToFile:atomically: method implemented in these
     classes to write your data to a file.
     
     Sample:
     Write to file:
     NSDictionary  *glossary;
     ....
     if ([glossary writeToFile: @ "glossary" atomically: YES] == NO)
         NSLog (@ "Save to file failed!");
     
     Read from file:
     NSDictionary *glossary;
     glossary = [NSDictionary dictionaryWithContentsOfFile: @ "glossary "];
     for ( NSString *key in glossary )
         NSLog (@"%@: %@ " ,  key, [glossary objectForKey: key]);
      
     
     
   • A more flexible approach enables you to save any type of objects to a file, not just strings, arrays, and dictionaries. This is done by creating a keyed archive using the NSKeyedArchiver class.
     
     Sample:
     Write to file:
     NSDictionary *glossary;
     ......
     [NSKeyedArchiver archiveRootObject: glossary toFile: @ "glossary.archive"];
     
     Read from file:
     NSDictionary *glossary;
     glossary = [NSKeyedUnarchiver unarchiveObjectWithFile:@"glossary.archive"];
     for ( NSString *key in glossary )
         NSLog (@ ” %@: %@ ” ,  key, [glossary objectForKey: key]);
     
   
   
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