CODEWITHSUNDEEP
iosobjective-cuiviewnsarraytime-complexity
slonkar
slonkar

Reputation: 4085

Check if NSArray contains object with specific property

I have an array of UIView. I want to check if that array contains UIView with specific tag. If it does then I should get that view or else I should receive nil.

As of now I using following 

// validCells is an array UIView

NSPredicate *p = [NSPredicate predicateWithBlock:^BOOL(id obj, NSDictionary *ignored){
            return ((UIView *)obj).tag == i;
        }];

UIView *cell = [[validCells filteredArrayUsingPredicate:p] lastObject];

This works fine but complexity is n^2. I was wondering if there is any other better way to do it.

Thanks.

Upvotes: 10

Views: 4757

Answers (1)

Martin R
Martin R

Reputation: 539775

I don't think the complexity of your method is O(n^2), it is more probably like O(n). But there is no reason to create a temporary array if you just search for a specific element. As @Josh said, you can do a simple enumeration.

If you want to be a bit more fancy, you can write it as

NSUInteger index = [validCells indexOfObjectPassingTest:^BOOL(UIView *view, NSUInteger idx, BOOL *stop) {
    return view.tag == idx;
}];
if (index != NSNotFound) {
    cell = validCells[index];
}

Upvotes: 25

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