Map Annotations Displayed on Date - ios

Question

I have a map that displays an array of annotations. These annotations are all called from a plist and each have a date at which they occur. I would like these annotations to display only on the date that they happen, however I have no clue how to approach this. Any help would be much appreciated.
for (NSString *dateString in contentArray) {
[[NSUserDefaults standardUserDefaults] stringForKey:#"Date"];
}
This is the little bit of code I have written in but it does not solve anything for me.
EDIT:
Here is the code that calls the annotations generally.
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
self.navigationController.navigationBarHidden = YES;
indexValue = 0;
NSString* plistPath = [[NSBundle mainBundle] pathForResource:#"mapAddress" ofType:#"plist"];
NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithContentsOfFile:plistPath];
NSString *strID = [NSString stringWithFormat:#"%d",intID];
NSLog(#"array : %#",[dict objectForKey:strID]);
[contentArray removeAllObjects];
[contentArray addObjectsFromArray:[dict objectForKey:strID]];
[contentArray retain];
[self zoomToUserLocation:mapViewuno.userLocation];
}
- (void)zoomToUserLocation:(MKUserLocation *)userLocation
{
if (!userLocation)
return;
MKCoordinateRegion region;
region.center = userLocation.location.coordinate;
region.span = MKCoordinateSpanMake(.5, .5);
region = [mapViewuno regionThatFits:region];
[mapViewuno setRegion:region animated:YES];
counter = 0;
[mapViewuno removeAnnotations:mapViewuno.annotations];
if([contentArray count] != 0)
{
for(indexValue = 0; indexValue<[contentArray count];indexValue++)
{
FirstAnnotation *obj=[[FirstAnnotation alloc]init];
obj.latitude = [[[contentArray objectAtIndex:indexValue] objectForKey:#"lattitude"] floatValue];
obj.longitude = [[[contentArray objectAtIndex:indexValue] objectForKey:#"Longitude"] floatValue];
obj.titleName=[[contentArray objectAtIndex:indexValue] objectForKey:#"Title"];
obj.Address = [[contentArray objectAtIndex:indexValue] objectForKey:#"Address"];
obj.Phone = [[contentArray objectAtIndex:indexValue] objectForKey:#"Phone"];
obj.intTag = indexValue;
[mapViewuno addAnnotation:obj];
}
if ([mapViewuno.annotations count] == 0) return;
// [self.mapView setRegion:newRegion animated:YES];
}
}