使用Objective-C 計算代碼運行時間

第一種：（最簡單的NSDate）

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

第二種：（將運行代碼放入下麵的Block中，返回時間）

#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;  
}

第三種：

/**
 * 計算腳本時間
 * @param $last 最後一次的運行clock
 * @param $key  標識
 * @return 當前clock
 */
double t(double last, char* key){
    clock_t now = clock();
    printf("time:%fs \t key:%s \n", (last != 0) ? (double)(now - last) / CLOCKS_PER_SEC : 0, key);
    return now;
}

double t1 = t(0, "");
//do something
t(t1, "end");