Is keepingCapacity when using array.removeAll more performant?

Question

Assuming we have an array

var foo = ["bar", "baz", "qux"]

...and we're going to re-populate that array with the same number of elements via multiple foo.append() calls, after we've removed all elements: is there any performance advantage to keeping the existing capacity of the array?

// Keep the capacity
foo.removeAll(keepingCapacity: true)

vs.

// Don't keep the capacity
foo.removeAll(keepingCapacity: false)

Answer 1

From the docs.

keepCapacity

Pass true to request that the collection avoid releasing its storage. Retaining the collection’s storage can be a useful optimization when you’re planning to grow the collection again. The default value is false.

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So the answer is yes i guess.