用GCD实现延迟执行任务
// [self performSelector:@selector(doSomething)
// withObject:nil
// afterDelay:5.0];
//Using dispatch_after
dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t) (5.0 * NSEC_PER_SEC));
dispatch_after(time, dispatch_get_main_queue(), ^(void) {
[self doSomething];
//签到
[selfuserSignView];
});
