Return NSArray from NSDictionary

Question

I have a fetch that returns an array with dictionary in it of an attribute of a core data object.

Here is my previous question: Create Array From Attribute of NSObject F

Answer 1

Call valueForKey on the array object returned from the fetch request. That will in-turn call valueForKey on each object and return an array of all resulting values.

NSArray *timestamps = [objects valueForKey:@"timeStamp"];

Answer 2

The Fast Enumeration method:

NSMutableArray *data = [[NSMutableArray alloc] initWithCapacity:array.count];
for (NSDictionary *d in objects) {
  [data addObject:[d objectForKey:@"timeStamp"]];
}

The Block enumerator method:

NSMutableArray *data = [[NSMutableArray alloc] initWithCapacity:array.count];
[objects enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
  [data addObject:[obj objectForKey:@"timeStamp"]];
}];

Either way, 'data' contains just an array of NSDate instances.

Answer 3

To get the type of array you want, you can do something like this:

NSMutableArray *array = [[NSMutableArray alloc] init];
for (int n = 0; n < [data count]; n++) // data array 
 {  
    NSMutableArray *array = [[NSMutableArray alloc] init];
    array = [NSMutableArray arrayWithObjects:[[data objectAtIndex:n] valueForKey:@"timeStamp"] ,nil];
   if ([array count] != 0) {
    [newArray addObject:[array objectAtIndex:0]];
    }
  }
 [array release];

hope this will help you!!

~Manoj