IOS 点击输入框外的屏幕空白处隐藏键盘

1. 在ViewController载入的时候，将键盘显示和消失的Notification添加到self.view里。

2. 分别在键盘显示和消失时添加和删除TapGestureRecognizer

- (void)viewDidLoad{    [super viewDidLoad];    [self setUpForDismissKeyboard];}- (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 {//此method会将self.view里所有的subview的first responder都resign掉  [self.view endEditing:YES];}