代码备忘：

1、点击空白处，收起键盘

UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(hideKeyBoard)];
tapGestureRecognizer.cancelsTouchesInView = NO;
[self.tableView addGestureRecognizer:tapGestureRecognizer];

- (void)hideKeyBoard {

    [self.textField endEditing:YES];
}

2、拨打电话

NSString *phoneStr = @"telprompt:400-8888888";
NSURL *url  =[NSURL URLWithString:phoneStr];
[[UIApplication sharedApplication] openURL:url];