BNRTimeBlock.h

CGFloat BNRTimeBlock (void (^block)(void));

BNRTimeBlock.m

#import <mach/mach_time.h>  // for mach_absolute_time() and friends

CGFloat BNRTimeBlock (void (^block)(void)) {
    mach_timebase_info_data_t info;
    if (mach_timebase_info(&info) != KERN_SUCCESS) return -1.0;

    uint64_t start = mach_absolute_time ();
    block ();
    uint64_t end = mach_absolute_time ();
    uint64_t elapsed = end - start;

    uint64_t nanos = elapsed * info.numer / info.denom;
    return (CGFloat)nanos / NSEC_PER_SEC;

} // BNRTimeBlock

main.m

#define LOOPAGE 10000000

#import "BNRTimeBlock.h"

int main (void) {
    CGFloat time;

    NSString *thing1 = @"hi";
    NSString *thing2 = @"hello there";

    time = BNRTimeBlock(^{
            for (int i = 0; i < LOOPAGE; i++) {
                [thing1 isEqual: thing2];
            }
        });
    printf ("isEqual: time: %f\n", time);

    time = BNRTimeBlock(^{
            for (int i = 0; i < LOOPAGE; i++) {
                [thing1 isEqualToString: thing2];
            }
        });
    printf ("isEqualToString: time: %f\n", time);

    return 0;
} // main