Question

I have an array which contains 2 objects. Each object has a “type” key. One of the values for that key is “resource” and the other is “crop”.

I want to sort through that array and create a new array which only contains the objects of the type I need. I thought this code did that…

-(NSArray*)getItemsOfType:(NSString *) type
{
    NSSortDescriptor *sortDescriptor;
    sortDescriptor = [[NSSortDescriptor alloc] initWithKey:type
                                                 ascending:YES];
    NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
    NSArray *sortedArray;
    sortedArray = [templateObjects sortedArrayUsingDescriptors:sortDescriptors];

    return sortedArray;
}

But all it seems to do is just sort the current array into some kind of order. How can I change that function to do what I need? so I need to use “initWithKey:ascending:selector:” ?

UPDATE

I just tried this code above the code above…

NSPredicate *predicate = [NSPredicate predicateWithFormat: @"templateObjects.type like %@", type];

    NSArray *newArray = [templateObjects filteredArrayUsingPredicate:predicate];

But newArray just appears to be empty? I have a feeling the @”templateObjects.type” part is wrong?

Update 2

ok this code does what I need it to..

-(NSArray*)getItemsOfType:(NSString *) type
{
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"type CONTAINS[cd] %@", type];

    NSArray *newArray = [templateObjects filteredArrayUsingPredicate:predicate];

    NSSortDescriptor *sortDescriptor;
    sortDescriptor = [[NSSortDescriptor alloc] initWithKey:type
                                                 ascending:YES];
    NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
    NSArray *sortedArray;
    sortedArray = [newArray sortedArrayUsingDescriptors:sortDescriptors];

    return sortedArray;
}

Answer 1

use

[NSPredicate predicateWithFormat: @"type like %@", type];

instead of

[NSPredicate predicateWithFormat: @"templateObjects.type like %@", type];

so

NSPredicate *predicate = [NSPredicate predicateWithFormat: @"type like %@", type];

or

NSPredicate *predicate = [NSPredicate predicateWithFormat: @"type CONTAINS[cd] %@", type];

This will work as you said both objects have the type key.