计算代码段所用时间

//计算代码段所用时间
NSDate* tmpStartData = [[NSDate date] retain];
/*( 要计算的代码段 )*/
//计算代码段所用时间
double deltaTime = [[NSDate date] timeIntervalSinceDate:tmpStartData];
NSLog(@">>>>>>>>>>nearshop cost time = %f ms", deltaTime*1000);