自定义导航栏上面有UITextField，但是当键盘弹出时候怎么点击视图弹下去呢？
不多说，贴出如下代码自己理解：

- (void)setUpForDismissKeyboard {
    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
    UITapGestureRecognizer *singleTapGR =
    [[UITapGestureRecognizer alloc] initWithTarget:self
                                            action:@selector(tapAnywhereToDismissKeyboard:)];
    NSOperationQueue *mainQuene =[NSOperationQueue mainQueue];
    [nc addObserverForName:UIKeyboardWillShowNotification
                    object:nil
                     queue:mainQuene
                usingBlock:^(NSNotification *note){
                    [self.view addGestureRecognizer:singleTapGR];
                }];
    [nc addObserverForName:UIKeyboardWillHideNotification
                    object:nil
                     queue:mainQuene
                usingBlock:^(NSNotification *note){
                    [self.view removeGestureRecognizer:singleTapGR];
                }];
}

- (void)tapAnywhereToDismissKeyboard:(UIGestureRecognizer *)gestureRecognizer {
    [self.search endEditing:YES];
}