Question

I have an array of objects, each containing a bool value with yes or no. I want to copy all objects with bool YES to another array. How can i do that? i have considered filtering the array using a predicate or integrating it in a for-loop, but i cant seem to get it right.

I need something like this:

for (BOOL* opslag_Set in [dataSource allKeys]){
    NSArray *array = [dataSource objectForKey:opslag_Set];
    for (int j = 0; j < [array count]; j++) {
        if ([[array objectAtIndex:j] isEqualToString:@"YES"]) {
            add object to another array;
        }
    }
}

First object of my array:

    },
    {
    Dato = "2012-11-07 16:20:57 +0000";
    Forfatter = "Vej 51, st. tv.";
    Indhold = "Referat af beboerm\U00f8de";
    "Opslag_set" = 0;
    Overskrift = "Beboerm\U00f8de";
    Prioritet = 0;
    Svar =         (
                    {
            Dato = "2012-11-07 16:23:07 +0000";
            Forfatter = "6. tv.";
            Indhold = "Fedt fedt fedt";
        }
    );
},

Answer 1

You will have to use NSNumber in order to store the bools in an array.

Assuming your boolean array is called boolArray, the code to get an array with only YES would be something like this:

NSMutableArray* temp = [NSMutableArray new];
for (NSNumber* value in boolArray)
{
    if ([value boolValue])
    {
        [temp addObject:[NSNumber numberWithBool:YES]];
    }
}

However, why are you trying to do this? This will return an array with a certain number of elements that are all the same. You could just count the number if that’s what you want. The other thing I can think of is that you have an object with a bool property, in which case you can easily adapt the code above.

EDIT: OK, let’s assume that we have an object called MyDataObject that has a bool property – NSNumber* boolProperty. Here is the code:

NSMutableArray* temp = [NSMutableArray new];
for (MyDataObject* value in boolArray)
{
    if ([value.boolProperty boolValue])
    {
        [temp addObject:value];
    }
}

This should work for what you are doing. temp will reference the original objects – they are not being copied.