Question

here is my dictionary and its values

NSMutableDictionary *myDic=[NSMutableDictionary Dictionary];
[myDIC setObject:@""];

[myDIC  setObject:string1 forKey:key1];
[myDIC  setObject:string2 forKey:key2];
[myDIC  setObject:string3 forKey:key3];

so up to here i have filled up my dictionary.now i want to read them through a for loop.

for (NSString *key in myDic ){


}

here is my problem! inside this loop the my first key will be key1 but i seems it start from the last key that i have set before!

is there anyone who can tell me why ? and how i can meet my expectation as what i explained?

Answer 1

NSDictionary is not an index base collection it’s a Hashtable, and like all HashTable, the elements are store according to some logic base on some Hash that you don’t know. If you look in the documentation for NSDictionary you will find a sentence that state that there is not guaranty about the order into which the item will be retrieve.
If you want your key to be retrieve in a specific order you will need to keep your keys in an NSArray, in the order that you want them.

---

Or you can sort your keys when you need them.

NSArray * allKeys = [myDict allKeys];
allKeys = [allKeys sortedArrayUsing//  [see the documentation for all options][1] ];