IOS 键盘使用

在点击录入框时键盘会自动升起，这是系统自动操作，但很多时候键盘会把视图中控件挡住，这样我们就得对键盘升做一些操作，

首先，要监听键盘升起事件，系统在升起键盘时会发出UIKeyboardWillShowNotification信号，要捕捉它并设置处理函数。

[[NSNotificationCenterdefaultCenter]addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];

keyboardWillShow是处理函数，在函数做视图位置上升变化。键盘处理函数中改变视图位置要注意个问题，如果键盘弹出不是英文键盘，会收到多次信号，这是因为系统在切换键盘时都会发出keyboardWillShow信号。比如现在使用的是中文输入法，系统首先弹出键盘是英文键盘会发出信号，然后在切换到中文键盘又会发出信号，

还要监听键盘降下事件，在键盘落下时把视图位置反回原处，键盘落下系统发出UIKeyboardWillHideNotification信号

[[NSNotificationCenterdefaultCenter]addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];

键盘处理函数

-(void) keyboardWillShow:(NSNotification *)note{

   //取得键盘位置高度

   CGRect keyboardBounds;

    [[note.userInfovalueForKey:UIKeyboardFrameEndUserInfoKey]getValue: &keyboardBounds];

    NSNumber *duration = [note.userInfoobjectForKey:UIKeyboardAnimationDurationUserInfoKey];

    NSNumber *curve = [note.userInfoobjectForKey:UIKeyboardAnimationCurveUserInfoKey];

    

    // Need to translate the bounds to account for rotation.

    keyboardBounds = [self.viewconvertRect:keyboardBoundstoView:nil];

    

    //改变视图位置

   CGRect containerFrame =containerView.frame;

    containerFrame.origin.y =self.view.bounds.size.height - keyboardBounds.size.height;

    // animations settings

    [UIViewbeginAnimations:nilcontext:NULL];

    [UIViewsetAnimationBeginsFromCurrentState:YES];

    [UIViewsetAnimationDuration:[durationdoubleValue]];

    [UIViewsetAnimationCurve:[curveintValue]];

    

    // set views with new info

   containerView.frame = containerFrame;

    

    

    // commit animations

    [UIViewcommitAnimations];

}

-(void) keyboardWillHide:(NSNotification *)note{

    NSNumber *duration = [note.userInfoobjectForKey:UIKeyboardAnimationDurationUserInfoKey];

    NSNumber *curve = [note.userInfoobjectForKey:UIKeyboardAnimationCurveUserInfoKey];

    

    // get a rect for the textView frame

   CGRect containerFrame =containerView.frame;

    containerFrame.origin.y =self.view.bounds.size.height - containerFrame.size.height +20;

    

    // animations settings

    [UIViewbeginAnimations:nilcontext:NULL];

    [UIViewsetAnimationBeginsFromCurrentState:YES];

    [UIViewsetAnimationDuration:[durationdoubleValue]];

    [UIViewsetAnimationCurve:[curveintValue]];

    

    // set views with new info

   containerView.frame = containerFrame;

    // commit animations

    [UIViewcommitAnimations];

}

也可以监听某些按件，让某个控件关闭键盘

-(IBAction)sendMessage_Click:(id)sender

{

    [textViewresignFirstResponder];

}