IOS 点击输入框外的屏幕空白处隐藏键盘

- (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];
}