监听键盘事件
注册监听键盘事件：
1 // 键盘即将隐藏
2 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
3
4 // 键盘已经隐藏
5 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];
6
7 // 键盘即将显示
8 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
9
10 // 键盘已经显示完毕
11 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
实现监听方法，在监听的方法中做自己的事情：
1 /**
2 * 键盘即将隐藏
3 */
4 - (void)keyboardWillHide:(NSNotification *)notification
5 {
6 NSLog(@"keyboardWillHide --> %@", notification);
7
8 // 获取键盘的动画时间
9 CGFloat duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
10 [UIView animateWithDuration:duration animations:^{
11
12 // 获取键盘的高度
13 CGRect keyboardRect = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
14
15 // 更改文本框的y值
16 CGRect fieldRect = self.textField.frame;
17 fieldRect.origin.y += keyboardRect.size.height;
18 self.textField.frame = fieldRect;
19 }];
20 }
21
22 /**
23 * 键盘已经隐藏完毕
24 */
25 - (void)keyboardDidHide:(NSNotification *)notification
26 {
27 NSLog(@"keyboardDidHide --> %@", notification);
28 }
29
30 /**
31 * 键盘即将显示
32 */
33 - (void)keyboardWillShow:(NSNotification *)notification
34 {
35 // 获取键盘动画时间
36 CGFloat duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
37 [UIView animateWithDuration:duration animations:^{
38
39 // 获取键盘的高度
40 CGRect keyboardRect = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
41
42 // 更改文本框的y值
43 CGRect fieldRect = self.textField.frame;
44 fieldRect.origin.y -= keyboardRect.size.height;
45 self.textField.frame = fieldRect;
46 }];
47 }
48
49 /**
50 * 键盘已经显示完毕
51 */
52 - (void)keyboardDidShow:(NSNotification *)notification
53 {
54 NSLog(@"keyboardDidShow --> %@", notification);
55 }
在控制器即将销毁时，移除键盘监听事件：
1 - (void)dealloc 2 { 3 // 移除键盘监听事件 4 [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil]; 5 6 [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil]; 7 8 [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil]; 9 10 [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidHideNotification object:nil]; 11 }
可以获取的userInfo属性值：
| 关键字 | 描述 |
| UIKeyboardAnimationCurveUserInfoKey | 动画曲线类型（UIViewAnimationCurve），数值是NSNumber |
| UIKeyboardAnimationDurationUserInfoKey | 动画持续时间，数值是NSNumber |
| UIKeyboardBoundsUserInfoKey | 键盘的大小 |
| UIKeyboardCenterBeginUserInfoKey | 键盘开始的中心点 |
| UIKeyboardCenterEndUserInfoKey | 键盘结束的中心点 |
| UIKeyboardFrameBeginUserInfoKey | 动画前键盘的位置，包含CGRect的NSValue |
| UIKeyboardFrameChangedByUserInteraction | 改变键盘的交互状态 |
| UIKeyboardFrameEndUserInfoKey | 动画结束后的键盘位置，包含CGRect的NSValue |
