自我mark一下。如下图所示：界面上有2个textField，当其成为第一响应者时弹出键盘且要求textField的父视图跟随键盘上移。另外要求时间标签上的时间实时显示。
实现原理：注册通知监听键盘的frame变化，从而改变textField父视图的bottom约束值。
示意图.gif
UIKeyboardAnimationCurveUserInfoKey = 7;//动画效果
UIKeyboardAnimationDurationUserInfoKey = "0.25";//键盘弹出动画时间
UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {375, 258}}";
UIKeyboardCenterBeginUserInfoKey = "NSPoint: {187.5, 796}";
UIKeyboardCenterEndUserInfoKey = "NSPoint: {187.5, 538}";
UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 667}, {375, 258}}";//键盘起始frame
UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 409}, {375, 258}}";//键盘弹出时frame
UIKeyboardIsLocalUserInfoKey = 1;
//1,注册通知，监听键盘frame变化
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];
-(void)keyboardWillChangeFrame:(NSNotification*)notification{
// NSLog(@"notification-info:%@",notification.userInfo);
//获取键盘弹起时y值
CGFloat keyboardY=[notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].origin.y;
//改变底部约束
self.bottomConstraint.constant=[UIScreen mainScreen].bounds.size.height-keyboardY;//bottomConstraint是textField的父视图距离self.View的底部距离
//获取键盘弹起时间
CGFloat duration=[notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
[UIView animateWithDuration: duration animations:^{
[self.view layoutIfNeeded];
}];
}
记得要在dealloc方法里移除通知：
//移除通知
[[NSNotificationCenter defaultCenter]removeObserver:self];
时间标签实时显示
//创建定时器,刷新时间
__weak KeyboardViewController *weakSelf=self;
_timer=[NSTimer timerWithTimeInterval:1 repeats:YES block:^(NSTimer * _Nonnull timer) {
KeyboardViewController *strongSelf=weakSelf;
[strongSelf updateTime];//使用strong是为了保证实例持续存活
}];
-(void)updateTime{
//设置时间label
NSDate *currentDate = [NSDate date];//获取当前时间、日期
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"YYYY-MM-dd hh:mm:ss"];
NSString *dateString = [dateFormatter stringFromDate:currentDate];
self.timeLabel.text=dateString;
}
