iOS nonatomic,atomic效率测试—(yaoyao)

#import "ViewController.h"

#import <UIKit/UIKit.h>

#import <mach/mach_time.h>   //要使用统计程序执行时间的函数，必须导入的头文件

#import <Foundation/Foundation.h>

@interface ViewController ()

@property(nonatomic,copy) NSString *nonatomicTest;

@property(atomic,copy) NSString *atomicTest;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

uint64_t start =  mach_absolute_time();

self.nonatomicTest = @"test";

uint64_t end   = mach_absolute_time();

NSLog(@"end - begin ＝ %llu",end-start);

uint64_t start1 =  mach_absolute_time();

self.atomicTest = @"test";

uint64_t end1   = mach_absolute_time();

NSLog(@"end1 - begin1 ＝ %llu",end1-start1);

//通过测试可以看出当声明为nonatomic，系统执行时能提高几倍的效率，所以在属性声明的时候，当该成员不会在多线程下访问时，尽量将它声明为为非原子性

}