1.键盘出现消失时，参考的view变化的代码：
- (void)viewDidLoad {
superviewDidLoad\]; // Do any additional setup after loading the view. __weaktypeof(self) weakSelf =self; _textField= \[UITextField new\]; _textField.backgroundColor = \[UIColor redColor\]; \[self.view addSubview:_textField\]; \[_textField mas_makeConstraints:\^(MASConstraintMaker \*make) { //left,right,centerx,y不能共存只能有其二 make.left.mas_equalTo(20); //make.right.mas_equalTo(-60); make.centerX.equalTo(weakSelf.view); make.height.mas_equalTo(40); make.bottom.mas_equalTo(0); }\]; //注册键盘通知 \[\[NSNotificationCenter defaultCenter\] addObserver:selfselector:@selector(keyboardWillChangeFrameNotification:) name:UIKeyboardWillChangeFrameNotification object:nil\]; \[\[NSNotificationCenter defaultCenter\] addObserver:selfselector:@selector(keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil\]; } * (void)keyboardWillChangeFrameNotification:(NSNotification \*)notification { //获取键盘基本信息（动画时长与键盘高度） NSDictionary \*userInfo = \[notification userInfo\]; CGRect rect = \[userInfo\[UIKeyboardFrameBeginUserInfoKey\] CGRectValue\]; CGFloat keyboardHeight= CGRectGetHeight(rect); CGFloat keyboardDuration = \[userInfo\[UIKeyboardAnimationDurationUserInfoKey\] doubleValue\]; //修改下边距约束 \[_textField mas_updateConstraints:\^(MASConstraintMaker \*make) { make.bottom.mas_equalTo(-keyboardHeight); }\]; //更新约束 \[UIView animateWithDuration:keyboardDuration animations:\^{ \[self.view layoutIfNeeded\]; }\]; } * (void)keyboardWillHideNotification:(NSNotification \*)notification { //获得键盘动画时长 NSDictionary \*userInfo= \[notification userInfo\]; CGFloat keyboardDuration = \[userInfo\[UIKeyboardAnimationDurationUserInfoKey\] doubleValue\]; //修改为以前的约束（距下边距0） \[_textField mas_updateConstraints:\^(MASConstraintMaker \*make) { make.bottom.mas_equalTo(0); }\]; //更新约束 \[UIView animateWithDuration:keyboardDuration animations:\^{ \[self.view layoutIfNeeded\]; }\]; } * (void)touchesBegan:(NSSet \*)touches withEvent:(UIEvent \*)event { \[supertouchesBegan:touches withEvent:event\]; \[self.view endEditing:YES\]; }