Update/change values of NSDictionary keys stored in NSArray - objective-c

Question

I have an NSArray containing NSDictionary's of client data. I am using NSPredicate to filter the array and pass it through ViewControllers with segues. I am at a stage where I would like to change some values of the keys stored in the dictionary. How is this achievable?
My prepareForSegue method
if ([[segue identifier] isEqualToString:#"showClients"]) {
// Detect selected row
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
// Extract value from the Clinic_Location attribute
NSString *cString = [[_clinicList valueForKey:#"Clinic_Location"] objectAtIndex:indexPath.row];
NSLog(#"Row pressed: %#", cString);
// Set predicate where Clinic_Location equals the clinic string extracted from the selected row
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"Clinic_Location == %#", cString];
// Filter the client array using this predicate
filteredClientArray = [dataStart filteredArrayUsingPredicate:predicate];
NSLog(#"Filtered array: %#", filteredClientArray);
// Reload the table
[self.tableView reloadData];
// Sort the array by Appt_Time in ascending order
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]initWithKey:#"Appt_Time" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
NSArray *sortedArray = [filteredClientArray sortedArrayUsingDescriptors:sortDescriptors];
filteredClientArray = [NSMutableArray arrayWithArray:sortedArray];
// Pass the newly filtered & sorted array to next view
PCClientsViewController *pcClients = segue.destinationViewController;
pcClients.clientArray = filteredClientArray;
}
The array now only contains certain dictionaries based on this predicate (i.e. when user selects a row on the TableView, let's say 'Manchester', then only dictionaries with a Clinic_Location of Manchester get passed to the next view.
My prepareForSegue method on the next TableView is similar to the previous one, in this case my predicate filters the dictionary with a matching surname on the selected row and pushes that to the next view. Now I am left with an array constructed like the one below:
Filtered array: (
{
"Appointment_Attended" = Yes;
"Appt_Time" = "2:00";
"Client_Address_Line_1" = "Ap #452-4253 Massa. Street";
"Client_Address_Line_2" = Montebello;
"Client_Address_Line_3" = Hull;
"Client_Address_Line_4" = Quebec;
"Client_Address_Line_5" = Micronesia;
"Client_Forename" = Veronica;
"Client_Postcode" = 69591;
"Client_Surname" = Ellis;
"Client_Tel" = "(019376) 26081";
"Clinic_Location" = Manchester;
"Passed_To_Medical" = No;
"Passed_To_Sol" = No;
}
)
I have tried many different approaches to update specific dictionary keys in this array such as using predicates, but nothing seems to work. For example:
NSPredicate* predicate = [NSPredicate predicateWithFormat:#"Client_Address_Line_1 == %#", [[_clientDetails valueForKey:#"Client_Address_Line_1"]objectAtIndex:0]];
NSLog(#"%#", predicate);
NSArray* filteredArray= [_clientDetails filteredArrayUsingPredicate: predicate];
[filteredArray performSelector: #selector(setValue:forKey:) withObject:self.clientAddLine1.text withObject:#"Client_Address_Line_1"];
No matter what I try I am continuously getting error messages such as:
*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__NSCFString 0x7904f590> setValue:forUndefinedKey:]: this
class is not key value coding-compliant for the key
Client_Address_Line_1.'
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDictionaryI
setObject:forKey:]: unrecognized selector sent to instance 0x78774c70'
*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<__NSDictionaryI 0x7bff6eb0> setValue:forUndefinedKey:]:
this class is not key value coding-compliant for the key
Client_Address_Line_1.'
It seems no matter what I do I cannot change or update any dictionary keys within the array. After hours of research, I'm beginning to wonder if this is this even possible? Am I looking at the wrong approach completely? Is there a better way to do this? After the keys have been changed, I need to save them back to the array and pass it back through ViewControllers also (possibly with Unwind Segues?) Any help is much appreciated.

Answer 1

You may only change the values for key in mutable subclasses of NSDictionary, NSDictionary itself is immutable.
so since you have changed to a mutable array, you can do the same thing for each of the dictionaries also:
filteredClientArray = [NSMutableArray arrayWithArray:sortedArray];
for(NSDictionary *d in [filteredClientArray copy])
{
NSMutableDictionary * m = [d mutableCopy];
[filteredClientArray replaceObjectAtIndex:[filteredClientArray indexOfObject:d] withObject:m];
}