CODEWITHSUNDEEP
objective-c
Curnelious
Curnelious

Reputation: 1

Fast way to check if array of dictionaries contain a dictionary with key?

I have array of NSDictionaries , in which i have to check if a dictionary with a certain key is exist, and it should be as fast as possible (done many times in real time )

To check if dic has key you have :

BOOL contains = [[dictionary allKeys] containsObject:obj];

or if([ dic objecetForKey:@"key"] != nil )

but to check the full array i have to run on all its objects ?

e.g

bool is=0;
for(nsdictionary *dic in array)
if([ dic objecetForKey:@"key"] != nil )
is=1;

//is says if i have the dic .

Upvotes: 2

Views: 4692

Answers (3)

Yaro
Yaro

Reputation: 1252

Another way:

Using NSPredicates 

NSPredicate *applePred = [NSPredicate predicateWithFormat:
                                      @"employer.name == 'Apple'"];
NSArray *appleEmployees = [people filteredArrayUsingPredicate:applePred];

or Using Blocks

- (BOOL)personExists:(NSString *)key withValue:(NSString *)value {

  NSPredicate *predExists = [NSPredicate predicateWithFormat:
                                         @"%K MATCHES[c] %@", key, value];
  NSUInteger index = [self.people indexOfObjectPassingTest:
                     ^(id obj, NSUInteger idx, BOOL *stop) {
                       return [predExists evaluateWithObject:obj];
                     }];

  if (index == NSNotFound) {
    return NO;
  }

  return YES;
}

[myArray indexOfObjectPassingTest:^(id obj, NSUInteger idx, BOOL *stop) {
    return [obj someTestForValue: value];
  }];

tutorial: http://useyourloaf.com/blog/2010/10/19/searching-arrays-with-nspredicate-and-blocks.html

Upvotes: 0

Daij-Djan
Daij-Djan

Reputation: 50089

KVC would look nice

NSArray *keys = [array valueForKeyPath:@"key"];
if([keys containsObject:@"myvalue"]) {
     NSLog(@"nice");
}

Upvotes: 9

idmean
idmean

Reputation: 14865

Your approach is good, but I would insert a break statement, because no further search is required if you have already found a dictionary.

bool is = NO;
for(NSDictionary *dic in array){
   if([dic objecetForKey:@"key"] != nil){
      is = YES;
      break;
   }
}

Upvotes: 1

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