CFAbsoluteTimeGetCurrent()函數(shù)能夠以毫秒為單位計(jì)算當(dāng)前時(shí)間與2001.1.1差值。

- (void)viewDidLoad {
    [super viewDidLoad];
    
    CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
    // do something

    CFAbsoluteTime end = CFAbsoluteTimeGetCurrent();

    NSLog(@"%f", end - start);
}