iOS获取一个方法的执行时间

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/