Xcode: Remove objects from NSMutableArray based on NSDictionary - xcode

Question

I am new to tableViews and dictionaries and i have a problem!
In ViewDidLoad i am initializing many MutableArrays and i am adding data using NSDictionary. Example:
- (void)viewDidLoad {
nomosXiou=[[NSMutableArray alloc] init];
[nomosXiou addObject:[[NSDictionary alloc] initWithObjectsAndKeys:#"Mary",#"name",#"USA",#"country", nil]];
[nomosXiou addObject:[[NSDictionary alloc] initWithObjectsAndKeys:#"Peter",#"name",#"Germany",#"country", nil]];
[super viewDidLoad];
// Do any additional setup after loading the view.}
In a previous ViewController the user selects a Country. Based on that selection, how could i remove from my arrays all the other entries???
Thanks in advance...

Answer 1

First note that your code fragment has an error. It should read:
NSMutableArray *nomosXiou= [[NSMutableArray alloc] init];
There are a number of ways to do what you want, but the most straightforward is probably the following:
NSString *countryName; // You picked this in another view controller
NSMutableArray *newNomosXiou= [[NSMutableArray alloc] init];
for (NSDictionary *entry in nomosXiou) {
if ([[entry objectForKey:#"country"] isEqualToString:countryName])
[newNomosXiou addObject:entry];
}
When this is done newNomosXiou will contain only the entries in nomosXiou that are from the country set in countryName.

Answer 2

Something like this will do the job:
NSMutableArray *nomosXiou = [[NSMutableArray alloc] init];
NSString *country = #"Germany"; // This is what you got from previous controller
// Some test data. Here we will eventually keep only countries == Germany
[nomosXiou addObject:[[NSDictionary alloc] initWithObjectsAndKeys:#"Mary",#"name",#"USA",#"country", nil]];
[nomosXiou addObject:[[NSDictionary alloc] initWithObjectsAndKeys:#"Peter",#"name",#"Germany",#"country", nil]];
[nomosXiou addObject:[[NSDictionary alloc] initWithObjectsAndKeys:#"George",#"name",#"Germany",#"country", nil]];
// Here we'll keep track of all the objects passing our test
// i.e. they are not equal to our 'country' string
NSIndexSet *indexset = [nomosXiou indexesOfObjectsPassingTest:^(id obj, NSUInteger idx, BOOL *stop){
return (BOOL)![[obj valueForKey:#"country"] isEqualToString:country];
}];
// Finally we remove the objects from our array
[nomosXiou removeObjectsAtIndexes:indexset];