iOS 监听键盘高度，输入框上升

//设置输入框 ---《因为输入框用了get方法，所以第一次调用输入框要用self 调用》；

    self.textlab.frame=CGRectMake(20, 420, 250, 30);
    _textlab.layer.borderColor=[UIColor blueColor].CGColor;
    _textlab.layer.borderWidth= 0.5f;
    _textlab.backgroundColor=[UIColor colorWithRed:0.830 green:0.801 blue:0.881 alpha:1.000];
    
    //添加输入框到视图
    [self.view addSubview:self.textlab];
    
    //监听键盘，键盘出现
    [[NSNotificationCenter defaultCenter]addObserver:self 
                                               selector:@selector(keyboardwill:) 
                                                   name:UIKeyboardWillShowNotification object:nil];

    //监听键盘隐藏
    [[NSNotificationCenter defaultCenter]addObserver:self 
                                               selector:@selector(keybaordhide:) 
                                                   name:UIKeyboardWillHideNotification object:nil];
    
    //设置点击手势，当点击空白处，结束编辑，收回键盘
    UITapGestureRecognizer *tapp=[[UITapGestureRecognizer alloc]
                                     initWithTarget:self action:@selector(tapAction:)];
    //开启交互
    self.view.userInteractionEnabled=YES;
    //添加手势到视图
    [self.view addGestureRecognizer:tapp];

 2、里面方法的实现

//点击手势方法
-(void)tapAction:(UITapGestureRecognizer *)sender
{
    [self.view endEditing:YES];
}

//当键盘出现时，调用此方法
-(void)keyboardwill:(NSNotification *)sender
{
    //获取键盘高度
    NSDictionary *dict=[sender userInfo];
    NSValue *value=[dict objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGRect keyboardrect = [value CGRectValue];
    int height=keyboardrect.size.height;
    
    //如果输入框的高度低于键盘出现后的高度，视图就上升；
    if ((_textlab.frame.size.height + _textlab.frame.origin.y)>(self.view.frame.size.height - height))
    {
        self.view.frame = CGRectMake(0, -height, self.view.frame.size.width, self.view.frame.size.height);
    }
}

//当键盘隐藏时候，视图回到原定
-(void)keybaordhide:(NSNotification *)sender
{
     self.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
}

//输入框的get方法
-(UITextField *)textlab
{
    if (_textlab==nil)
    {
        _textlab=[UITextField new];
    }
    return _textlab;
}

 防止键盘遮挡方式二;

调用UITextField 输入框的代理方法 <UITextFieldDelegate>

//开始编辑输入框的时候，软键盘出现，执行此事件
-(void)textFieldDidBeginEditing:(UITextField *)textlab
{
    //获取当前输入框的位置信息
    CGRect frame = textlab.frame;
    //获取键盘底部位置与键盘最高点之间的距离，键盘高度256
    int offset = frame.origin.y + frame.size.height - (self.view.frame.size.height - 256.0);
    //设置视图上升的时间
    NSTimeInterval animaTime = 0.30f;
    //字符串随意也行...
    [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
    //添加视图上的上升时间0.3f
    [UIView setAnimationDuration:animaTime];
    
    //将视图的Y坐标向上移动offset个单位，以使下面腾出地方用于软键盘的显示
    if(offset > 0)
        self.view.frame = CGRectMake(0.0f, -offset, self.view.frame.size.width, self.view.frame.size.height);
    //提交动画
    [UIView commitAnimations];
}

//当用户按下return键或者按回车键，keyboard消失
-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    //收回键盘第一响应者意思...
    [textField resignFirstResponder];
    return YES;
}

//输入框编辑完成以后，将视图恢复到原始状态
-(void)textFieldDidEndEditing:(UITextField *)textField
{
    self.view.frame =CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
}