判断app第一次被打开

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    BOOL firstTime = [[NSUserDefaults standardUserDefaults] integerForKey:@"FirstLaunch"];
    if (!firstTime) {
        [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"FirstLaunch"];
        NSLog(@"first lanch!");
}
    return YES;
}