iphone - NSArray of united Arrays

Question

I have an NSArray of objects called MMPlace, which has NSArray of MMProduct objects.

How do I get a united NSArray of all MMProduct objects that my Array of MMPlace object contains? Something like NSArray *arr = [array valueForKeyPath:@"@unionOfObjects.products"]; would be nice, though this specific example doesn't work.

Answer 1

You can do this with @unionOfArrays. The bit you were missing is that because the arrays are directly nested, the key on the right of the collection operator must be self:

NSArray *nestedValues = @[@[@1, @2, @3], @[@4, @5, @6]]
NSArray *flattenedValues = [nestedValues valueForKeyPath:@"@unionOfArrays.self"];
// flattenedValues contains @[@1, @2, @3, @4, @5, @6]