Objective-C benchmark utility class used in some of my projects

Benchmark.h

//
//  Benchmark.h
//  Opskrifter
//
//  Created by Sijawusz Pur Rahnama on 03/02/09.
//  Copyleft 2009. Some rights reserved.
//

#import <Foundation/Foundation.h>


@interface Benchmark : NSObject {
@protected
    NSString * _name;
    NSDate * _startTime;
    NSDate * _endTime;
}

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSDate * startTime;
@property (nonatomic, retain) NSDate * endTime;

// quick access class methods
+ (id) report:(NSString *)info with:(void (^)(void))block;

// singleton instances
+ (Benchmark *) instanceWithName:(NSString *)name;

// initializers
+ (id) benchmarkWithName:(NSString *)name;
- (id) initWithName:(NSString *)name;

// block method
- (id) run:(void (^)(void))block;

// benchmark methods
- (id) start;
- (id) stop;
- (id) log;

@end

Benchmark.m

//
//  Benchmark.m
//  Opskrifter
//
//  Created by Sijawusz Pur Rahnama on 03/02/09.
//  Copyleft 2009. Some rights reserved.
//

#import "Benchmark.h"


@implementation Benchmark

static NSMutableDictionary * __sharedBenchmarks = nil;

+ (NSMutableDictionary *) sharedBenchmarks {
    if (!__sharedBenchmarks) {
        __sharedBenchmarks = [[NSMutableDictionary alloc] init];
    }
    return __sharedBenchmarks;
}

+ (id) instanceWithName:(NSString *)name {
    @synchronized (self) {
        // get the benchmark or create it on-the-fly
        id benchmark = [[self sharedBenchmarks] objectForKey:name];
        if (!benchmark) {
            benchmark = [self benchmarkWithName:name];
            [[self sharedBenchmarks] setObject:benchmark forKey:name];
        }
        return benchmark;
    }
    return nil;
}

@synthesize name      = _name;
@synthesize startTime = _startTime;
@synthesize endTime   = _endTime;

# pragma mark -
# pragma mark Quick access class methods

+ (id) report:(NSString *)info with:(void (^)(void))block {
    return [[self instanceWithName:info] run:block];
}

# pragma mark -
# pragma mark Initializers

+ (id) benchmarkWithName:(NSString *)name {
    return [[[self alloc] initWithName:name] autorelease];
}

- (id) initWithName:(NSString *)name {
    if (self = [self init]) {
        self.name = name;
    }
    return self;
}

# pragma mark -
# pragma mark Benchmark methods

- (id) run:(void (^)(void))block {
    [self start];
    block();
    [self stop];
    return self;
}

- (id) start {
    NSDate * start = [[NSDate alloc] init];
    self.startTime = start;
    [start release];

    self.endTime = nil;
    return self;
}

- (id) stop {
    NSDate * stop = [[NSDate alloc] init];
    self.endTime = stop;
    [stop release];

    [self log];
    return self;
}

- (id) log {
    NSTimeInterval timeElapsed;
    if (_endTime)  timeElapsed = [_endTime timeIntervalSinceDate:_startTime];
    else           timeElapsed = [_startTime timeIntervalSinceNow] * -1.f;

    // log elapsed time
    if (_name)   NSLog(@"Benchmark '%@' took %f seconds.", _name, timeElapsed);
    else         NSLog(@"Benchmark took %f seconds.", timeElapsed);
    return self;
}
    
@end