Testing performance of filling an NSMutableArray

main.m

//
//  main.m
//  ArrayInitialization
//
//  Created by Anson Jablinski on 5/2/16.
//  Copyright © 2016 ForeFlight. All rights reserved.
//

#import <Foundation/Foundation.h>

NSNumber *newNumber() {
    return @(arc4random_uniform(1000));
}

NSNumber *runExperiment(NSNumber*(^testBlock)(void), NSUInteger iterations) {
    NSNumber *sum = @0;
    for (int count = 0; count < iterations; ++count) {
        sum = @(sum.doubleValue + testBlock().doubleValue);
    }
    return @(sum.doubleValue / @(iterations).doubleValue);
}

void printExperiment(NSString *name, NSString *description, NSUInteger iterations, NSNumber*(^testBlock)(void)) {
    NSNumber *result = runExperiment(testBlock, iterations);
    NSLog(@"\n%@ took %@ sec on average\n%@\n\n", name, result, description);
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSUInteger experimentIterations = 10000;
        
        printExperiment(@"addObject", @"[NSMutableArray array], then addObject:", experimentIterations, ^NSNumber *{
            NSMutableArray *array = [NSMutableArray array];
            double startTime = [NSDate timeIntervalSinceReferenceDate];
            for (int i = 0; i < 50; ++i) {
                [array addObject:newNumber()];
            }
            return @([NSDate timeIntervalSinceReferenceDate] - startTime);
        });
        
        printExperiment(@"addObjectWithCapacity", @"[NSMutableArray arrayWithCapacity:], then addObject:", experimentIterations, ^NSNumber *{
            NSMutableArray *array = [NSMutableArray arrayWithCapacity:50];
            double startTime = [NSDate timeIntervalSinceReferenceDate];
            for (int i = 0; i < 50; ++i) {
                [array addObject:newNumber()];
            }
            return @([NSDate timeIntervalSinceReferenceDate] - startTime);
        });
        
        printExperiment(@"assignment", @"[NSMutableArray arrayWithArray:] using literal @[] notation", experimentIterations, ^NSNumber *{
            NSMutableArray *array = nil;
            double startTime = [NSDate timeIntervalSinceReferenceDate];
            array = [NSMutableArray arrayWithArray:@[  // 5 x 10 = 50
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                                                     newNumber(), newNumber(), newNumber(), newNumber(), newNumber()
                                                     ]];
            return @([NSDate timeIntervalSinceReferenceDate] - startTime);
        });
        
        printExperiment(@"immutable assignment", @"NSArray *array = @[...];", experimentIterations, ^NSNumber *{
            double startTime = [NSDate timeIntervalSinceReferenceDate];
            NSArray *array = @[  // 5 x 10 = 50
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber(),
                               newNumber(), newNumber(), newNumber(), newNumber(), newNumber()
                               ];
            return @([NSDate timeIntervalSinceReferenceDate] - startTime);
        });
    }
    return 0;
}