how to remove object from NSDictionary

Question

Hi i am having a NSdictionary in which i am adding a array with key "countries ". Now i take the value of this dictionary into array and sort the array in alpahbatical order .Now i want to add this array into my Dictionary (that is i want to update my dictionary with new sorted array and remove the old array from it )........ how to do this

My code is as follows

NSArray *countriesToLiveInArray = [NSArray arrayWithObjects:@"Iceland", @"Greenland", @"Switzerland", @"Norway", @"New Zealand", @"Greece", @"Italy", @"Ireland", nil];
NSDictionary *countriesToLiveInDict = [NSDictionary dictionaryWithObject:countriesToLiveInArray forKey:@"Countries"];


NSArray *tmpary = [countriesToLiveInDict valueForKey:@"Countries"];
NSLog(@"ary value is  %@",ary);
NSArray *sortedArray = [tmpary sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)];
NSLog(@"sortedArray is %@",sortedArray);

Here i want to remove the countriesToLiveInArray and replace it with sortedArray with same key value i.e. Countries Thanks in advance..

Anthropomorphic

Why not just sort the array before adding it the to dictionary? – Surratt

Use objectForKey: not valueForKey: valueForKEy: is technically for KVC and it's very slightly slower. – Marandamarasca

Answer 1

First you need to use a NSMutableDictionary and put this code :

[countriesToLiveInDict removeObjectForKey:@"Countries"];
[countriesToLiveInDict setObject:sortedArray forKey:@"Countries"];

Trashy

You don't need to remove the previous object for the key. -setObject:forKey: automatically releases the previous object, if called on a kety that already exists. – Marandamarasca

Answer 2

First of all make your NSDictionary to NSMutableDictionary & then write the following line of code

[countriesToLiveInDict removeObjectForKey:@"Countries"];

This will definitely resolve your issue.

Conjugal

Is setting the countriesToLiveInDict = necessary? – Lissettelissi

Don't do this, the documentation states -[NSMutableDictionary removeObjectForKey:] returns void. See: - (void)removeObjectForKey:(KeyType)aKey – Cynthia

Answer 3

NSDictionary cannot remove anything, please use NSMutableDictionary, like this:

NSMutableDictionary *countriesToLiveInDict = [NSMutableDictionary dictionaryWithObject:countriesToLiveInArray forKey:@"Countries"];

Relief

Answer 4

for Swift 3 as @MathieuF answered it First you need to use a NSMutableDictionary and put this code :

countriesToLiveInDict.removeObject(forKey: "Countries")

i post my answer as i was search for same question and get inspired by @MathieuF

Laclos