最后在做一个应用的时候,从电话本时读出数据,如果电话很多,就需要比较长的时间,于是如果能得到每个方法的执行时间,就可以知道代码优化的地方。
在网上看到了一个比较好的方法来获取执行时间。看代码
#import <mach/mach_time.h> // for mach_absolute_time() and friends CGFloat BNRTimeBlock (void (^block)(void)) { mach_timebase_info_data_t info; if (mach_timebase_info(&info) != KERN_SUCCESS) return -1.0; uint64_t start = mach_absolute_time (); block (); uint64_t end = mach_absolute_time (); uint64_t elapsed = end - start; uint64_t nanos = elapsed * info.numer / info.denom; return (CGFloat)nanos / NSEC_PER_SEC; } // BNRTimeBlock
调用方法如下
#define LOOPAGE 10000000 #import "BNRTimeBlock.h" int main (void) { CGFloat time; NSString *thing1 = @"hi"; NSString *thing2 = @"hello there"; time = BNRTimeBlock(^{ for (int i = 0; i < LOOPAGE; i++) { [thing1 isEqual: thing2]; } }); printf ("isEqual: time: %f\n", time); time = BNRTimeBlock(^{ for (int i = 0; i < LOOPAGE; i++) { [thing1 isEqualToString: thing2]; } }); printf ("isEqualToString: time: %f\n", time); return 0; } // main
来自:http://weblog.bignerdranch.com/?p=316
还有一个: http://www.fieryrobot.com/blog/2010/07/10/a-watchdog-timer-in-gcd/