I have 2 NSMutableArrays. First array contains custom object intances with property NSString *itemID, second array contains only from NSString objects with same values of itemID, but in another order. I need to sort first array by itemID property of each object, and it should be sorted like second array.
How I can do this?
guideArray = < YOUR SECOND ARRAY WITH STRING OBJECT >;
unsortedArray = < YOUR FIRST ARRAY WITH CUSTOM OBJECT >;
[unsortedArray sortUsingComparator:^(id o1, id o2) {
Items *item1 = o1;
Items *item2 = o2;
NSInteger idx1 = [guideArray indexOfObject:item1.ItemID];
NSInteger idx2 = [guideArray indexOfObject:item2.ItemID];
return idx1 - idx2;
}];
NSLog(@"%@",unsortedArray);
Store the custom objects in an dictionary with itemID as key, use this dictionary as lookup to sort the objects:
NSArray *objects; // your objects
NSMutableArray *hintArray; // your sorted IDs
NSMutableDictionary *lookupDict = [[NSMutableDictionary alloc] initWithCapacity:[objects count]];
NSMutableArray *sortedObjects = [[NSMutableArray alloc] initWithCapacity:[hintArray count]];
for (id object in objects) {
[lookupDict setValue:object forKey:[object itemID]];
}
for (id hint in hintArray) {
[sortedObjects addObject:[lookupDict valueForKey:hint]];
}
EDIT:
Solution with inplace sort of objects:
NSMutableArray *objects;
NSMutableArray *hintArray;
NSMutableDictionary *lookupDict = [[NSMutableDictionary alloc] initWithCapacity:[hintArray count]];
int i = 0;
for (NSString *itemID in hintArray) {
[lookupDict setValue:[NSNumber numberWithInt:i] forKey:itemID];
i++;
}
[objects sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [[lookupDict valueForKey:[obj1 itemID]] compare:[lookupDict valueForKey:[obj2 itemID]]];
}];
You can compare your two objects using following syntax :-
[items sortUsingComparator:^NSComparisonResult(Attribute *obj1, Attribute *obj2)
{
return [[NSNumber numberWithInt:[stringOrder indexOfObject:obj1.itemID]] compare:[NSNumber numberWithInt:[stringOrder indexOfObject:obj2.itemID]]]
}];
or else you can use following snippet :
NSArray* sortedKeys = [dict keysSortedByValueUsingComparator:^(id obj1, id obj2)
{
return [obj1 compareTo:obj2];
}
Enjoy Programming !
