How do I measure the performance of the blocks inside the function in iOS Unit Testing

Function type to be tested:

[self someFunctionOnSuccess:^{

    //Test this block with a test case and check its performance

} onFailure:^{

    //Test this block with a test case and check its performance

}];

There are different test cases that I could write for passing and failing the function.

My Question is: How to measure the performace of these closures or blocks after they have completed the execution. For a simple method I could straight away use:

- (void)testPerformance {

    [self measureBlock:^{
         //Test the performance of this function.
        [self simpleFunction];

     }];

}