一、发送通知
1 NSNotification *note = [NSNotification notificationWithName:@"通知的名称，随便写，例如：你妈叫你回家吃饭" object:self userInfo:@{@"time":@"11:30", 2 @"desc":@"回家吃饭" 3 }]; 4 NSNotificationCenter *center = [NSNotificationCenter defaultCenter]; 5 [center postNotification:note];
二、接收通知：
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardChange:) name:UIKeyboardWillChangeFrameNotification object:nil];
三、键盘处理小练习
注意事项：tableView的高度约束取消，如果约束在的话，tableView无法实现上移，只能实现往上压缩
正确做法：设置tableView的高度约束等于父类约束的高度减去最下面工具栏的高度，如图：
<1>将键盘的显示和隐藏分开处理的情况
接收通知的代码：
1 - (void)viewDidLoad { 2 [super viewDidLoad]; 3 // addObserver-谁来接收 @Selector-接收完成需要执行的方法，带一个参数，接收通知中心发来的NSNotofication对象 4 // object-发送消息的对象，nil-不管谁发送的，只要是name中的消息都接收，这里监听的是键盘的即将弹出的消息，系统发出的消息是字符串常亮 5 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil]; 6 // 接收键盘隐藏的通知 7 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil]; 8 }
接收到通知后的处理代码：
1 - (void)keyboardWillShow:(NSNotification *)note 2 { 3 // 取出时间 4 CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]; 5 // 取出键盘显示出来后的最终frame 6 CGRect rect = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue]; 7 // 改变约束 8 self.bottomSpacing.constant = rect.size.height; 9 // 动画效果 10 [UIView animateWithDuration:duration animations:^{ 11 [self.view layoutIfNeeded]; 12 }]; 13 } 14 15 - (void)keyboardWillHide:(NSNotification *)note 16 { 17 // 取出时间 18 CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]; 19 // 约束改为0 20 self.bottomSpacing.constant = 0; 21 [UIView animateWithDuration:duration animations:^{ 22 [self.view layoutIfNeeded]; 23 }]; 24 }
<2>将键盘显示和隐藏一起处理的情况
- (void)viewDidLoad { [super viewDidLoad]; // 接收通知 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardChange:) name:UIKeyboardWillChangeFrameNotification object:nil]; }
1 - (void)keyboardChange:(NSNotification *)note 2 { 3 // 取出时间 4 CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]; 5 // 取出键盘最终的frame 6 CGRect rect = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue]; 7 self.bottomSpacing.constant = [UIScreen mainScreen].bounds.size.height - rect.origin.y; 8 [UIView animateWithDuration:duration animations:^{ 9 [self.view layoutIfNeeded]; 10 }]; 11 }
1 - (void)keyboardChange:(NSNotification *)note 2 { 3 // 取出时间 4 CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]; 5 // 取出键盘最终的frame 6 CGRect rect = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue]; 7 self.bottomSpacing.constant = [UIScreen mainScreen].bounds.size.height - rect.origin.y; 8 [UIView animateWithDuration:duration animations:^{ 9 [self.view layoutIfNeeded]; 10 }]; 11 }
四、最后一步，也是最重要的一步，记得取消注册的通知监听器
- (void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; }