Plist Array to NSDictionary

Question

I have a plist:

  
    
      name
      Alabama
          


        

Answer 1

The two problems:

• Loading the plist into an NSDictionary:

This is a simple problem, which it seems you have already figured out. The global object in your plist is an array, not a dict, so when you load it into the dictionary, it doesn't know what to do (incompatable types), so you're getting an empty dictionary.

• Looping through the array of dictionaries:

From the Exception you're getting, you are calling 'setObject:forKey:' on the dictionary, which is initialized as an NSDictionary, not an NSMutableDictionary. The pointer is typed as NSMutableDictionary, but not the actual in memory object. You need to change your line from.

NSMutableDictionary *myDic = [[NSDictionary alloc] initWithContentsOfFile:path];

to

NSMutableDictionary *myDic = [[NSMutableDictionary alloc] initWithContentsOfFile:path];

and actually, since loading the dictionary from the file gives you an empty dictionary, you are wasting cycles trying to load it from the file, and should just create a new one:

NSMutableDictionary *myDic = [[NSMutableDictionary alloc] init];

Answer 2

A more flexible way to load plists into memory, that also allows you to create mutable plists:

NSData* data = [NSData dataWithContentsOfFile:path];
NSMutableArray* plist = [NSPropertyListSerialization propertyListFromData:data
                                                         mutabilityOption:NSPropertyListImmutable
                                                                   format:NSPropertyListXMLFormat_v1_0
                                                         errorDescription:NULL];

Thus your code could be implemented as:

NSString *path = [[NSBundle mainBundle] pathForResource:@"stateInfo" ofType:@"plist"];
NSData* data = [NSData dataWithContentsOfFile:path];
NSMutableArray* array = [NSPropertyListSerialization propertyListFromData:data
                                                         mutabilityOption:NSPropertyListImmutable
                                                                   format:NSPropertyListXMLFormat_v1_0
                                                         errorDescription:NULL];
if (array) {
  NSMutableDictionary* myDict = [NSMutableDictionary dictionaryWithCapacity:[array count]];
  for (NSDictionary* dict in array) {
    State* state = [[State alloc] initWithDictionary:dict];
    [myDict setObject:state forKey:state.name;
    [state release];
  }
  NSLog(@"The count: %i", [myDic count]);
} else {
  NSLog(@"Plist does not exist");
}