How can I run my performance tests more than ten times?

Question

By default Xcodes performance tests are run ten times and my result is the average of those ten tests. The problem is the averaged result varies considerably each time I run it

Answer 1

In the latest Xcode (11.0+) you don't need swizzling to change iterations count. Use the following function:

func measure(options: XCTMeasureOptions, block: () -> Void)

This will allow you to specify XCTMeasureOptions which has iterationCount property.

Interesting note from docs:

A performance test runs its block iterationCount+1 times, ignoring the first iteration and recording metrics for the remaining iterations. The test ignores the first iteration to reduce measurement variance associated with “warming up” caches and other first-run behavior.