我可以从 plist 中读取密钥吗？

Question

Can I read just the key from plist without its value, also if I know the value can I read the key?

Answer 1

Reading.plist:

NSString *path = [[NSBundle mainBundle] pathForResource:@"myPlist" ofType:@"plist"];    
NSMutableDictionary *myDictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:path];

Getting all keys and all values:

NSArray* allmyKeys = [myDictionary  allKeys];
NSArray* allmyValues= [myDictionary  allValues];

Getting all keys for an values object:

NSArray* allmyKeys = [myDictionary  allKeysForObject:myValueObject];

Answer 2

As an alternative, you can use allKeysForObject: method which returns,

A new array containing the keys corresponding to all occurrences of anObject in the dictionary. If no object matching anObject is found, returns an empty array.

From that array you can get the key by invoking the objectAtIndex: method.

Answer 3

In order to read the values at app's installed folder:

 NSString *PListName=@"ExamplePlist";
 NSString *_PlistNameWithExtension=[NSString stringWithFormat:@"%@.plist",PlistName];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1
NSString *documentsDirectory = [paths objectAtIndex:0]; //2
NSString *path = [documentsDirectory stringByAppendingPathComponent:_PlistNameWithExtension]; //3

NSDictionary *myDictionary = [[NSDictionary alloc] initWithContentsOfFile:path];
NSLog(@"%@",[myDictionary description]); 
NSArray *AllKeys=[myDictionary allKeys];

Jhaliya's method has not worked for me, then I tried this method.

Answer 4

Use -[NSDictionary allKeysForObject:] *.

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Example

NSArray *keys = [myDict allKeysForObject:@"My Value"];
if ([keys count] != 0) { // to prevent out-of-bounds crashes
  NSString *key = [keys objectAtIndex:0];
  return key;
} else {
  return nil;
}

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^{_{*Dunno why it returns an NSArray object instead of an NSSet object, because keys are not ordered. Oh well.}}