fast enumeration vs. block enumeration

gistfile1.m

//
//  main.m
//  fastenumvsblockenum


#import <Foundation/Foundation.h>


@implementation NSMutableArray (RandomUtils)
-(void)shuffle
{
  NSUInteger count = [self count];
    for (NSUInteger i = 0; i < count; ++i) {
        NSUInteger nElements = count - i;
        NSUInteger n = (arc4random() % nElements) + i;
        [self exchangeObjectAtIndex:i withObjectAtIndex:n];
    }
}

@end



NSTimeInterval timeMaxMinfastenum(NSArray *array, NSUInteger repeats)
{
    float xmaxFastEnum = -MAXFLOAT;
    float xminFastEnum = MAXFLOAT;
    
    NSDate *startDate = [NSDate date];
    for (int i=0 ; i<repeats; ++i)
        for (NSNumber *num in array) {
            float x = [num floatValue];
            if (x < xminFastEnum) xminFastEnum = x;
            if (x > xmaxFastEnum) xmaxFastEnum = x;
        }
    NSTimeInterval end = [[NSDate date] timeIntervalSinceDate:startDate];
    return end;
}


NSTimeInterval timeMaxMinBlockEnum(NSArray *array, NSUInteger repeats)
{
    __block float xmaxFastEnum = -MAXFLOAT;
    __block float xminFastEnum = MAXFLOAT;
    
    NSDate *startDate = [NSDate date];
    for (int i=0 ; i<repeats; ++i)
        [array enumerateObjectsUsingBlock:^(NSNumber *num, NSUInteger idx, BOOL *stop) {
            float x = [num floatValue];
            if (x < xminFastEnum) xminFastEnum = x;
            if (x > xmaxFastEnum) xmaxFastEnum = x;
        }];
    NSTimeInterval end = [[NSDate date] timeIntervalSinceDate:startDate];
    return end;
}




int main(int argc, const char * argv[])
{

    @autoreleasepool {
        NSUInteger times = 100;
        NSUInteger n = 1000000;
        
        NSMutableArray *hugeArray = [NSMutableArray arrayWithCapacity:n];
        
        for (int i=0 ; i<n; ++i) {
            [hugeArray addObject:@(i)];
        }
        
         [hugeArray shuffle];
        
        for(NSUInteger j = 0; j< 30; ++j) {
            
            NSTimeInterval fn, bn;
            if(j % 2){
                fn = timeMaxMinfastenum(hugeArray, times);
                bn = timeMaxMinBlockEnum(hugeArray, times);
            } else {
                bn = timeMaxMinBlockEnum(hugeArray, times);
                fn = timeMaxMinfastenum(hugeArray, times);

            }
            NSLog(@"fast enum: %f \t block enum: %f \t %@", fn, bn, (fn < bn )? @"fast enum" : @"block enum");
        }
    }
    return 0;
}