Calculate your App Launching time

//Appdelegate.h
CFAbsoluteTime StartTime;  
@interface AppDelegate : UIResponder <UIApplicationDelegate>

@end

//In your main.m start your timer
int main(int argc, char *argv[])
{
    StartTime = CFAbsoluteTimeGetCurrent();
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

//Finally in your AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    dispatch_async(dispatch_get_main_queue(), ^{
        NSLog(@"Launched in %f sec", CFAbsoluteTimeGetCurrent() - StartTime);
    });
.....
}