延时方法

//status为failed时，实现弹出框
NSString *msg = [json objectForKey:@"msg"];
        [MBProgressHUD showMessag:msg toView:self.view afterDelay:1.0];
        //延时方法
        [self performSelector:@selector(delaySelector:) withObject:self afterDelay:1.0];


- (void)delaySelector:(id)sender {
    [self.navigationController popViewControllerAnimated:YES];
}