测试一段iOS代码运行时间的两种方法

iOS设备相对于电脑，内存和处理能力有限，所以一段代码或者程序运行的时间需要时刻注意，这里提供两种获取精确时间的方法。

方法一：使用系统时间

NSDate* tmpStartData = [[NSDate date] retain];
//You code here...
double deltaTime = [[NSDate date] timeIntervalSinceDate:tmpStartData];
NSLog(@">>>>>>>>>>cost time = %f ms", deltaTime*1000);

方法二：

#import <mach/mach_time.h>

uint64_t start = mach_absolute_time();

//You code here...

uint64_t end = mach_absolute_time();

uint64_t elapsed = end - start;mach_timebase_info_data_t info;

if (mach_timebase_info (&info) != KERN_SUCCESS)

{

printf ("mach_timebase_info failed\n");

}

uint64_t nanosecs = elapsed * info.numer / info.denom;

uint64_t millisecs = nanosecs / 1000000;

NSLog(@">>>>>>>>>>cost time = %ld ms", millisecs);