// 解決鍵盤遮擋問題
//選擇didShow是因為需要鍵盤的高度
//選擇willHide是因為視圖frame重置需要優先于鍵盤消失，否則表現得不連貫
      [[NSNotificationCenter defaultCenter] addObserver:self                                               selector:@selector(keyboardWasShown:)                                                   name:UIKeyboardDidShowNotification                                                 object:nil];        [[NSNotificationCenter defaultCenter] addObserver:self                                             selector:@selector(keyboardWasHide:)                                                 name:UIKeyboardWillHideNotification                                               object:nil];

-(void)keyboardWasShown:(NSNotification*)notification{    //獲取鍵盤高度    NSValue* value=notification.userInfo[UIKeyboardFrameBeginUserInfoKey];    CGFloat keyBoradHeight=[value CGRectValue].size.height;    NSNumber* animationTime=notification.userInfo[UIKeyboardAnimationDurationUserInfoKey];    double time=[animationTime doubleValue];    //獲取被遮擋控件距離controller底部的距離    float a=self.view4.frame.origin.y+self.view4.frame.size.height;    float b = self.view.frame.size.height-a;    if (b<keyBoradHeight)    {        //動畫效果        [UIView animateWithDuration:time                         animations:^         {             //鍵盤被擋住了             CGRect viewCGrect=self.view.frame;             //視圖應該上移所以是－             viewCGrect.origin.y=viewCGrect.origin.y-(keyBoradHeight-b);             [self.view setFrame:viewCGrect];         } completion:nil];    }}-(void)keyboardWasHide:(NSNotification*)notification{    NSValue* value=notification.userInfo[UIKeyboardFrameBeginUserInfoKey];    CGFloat keyBoradHeight=[value CGRectValue].size.height;    float a=self.view4.frame.origin.y+self.view4.frame.size.height;    float b = self.view.frame.size.height-a;             CGRect viewCGrect=self.view.frame;         viewCGrect.origin.y=viewCGrect.origin.y+(keyBoradHeight-b);         [self.view setFrame:viewCGrect];}

-(void)viewWillDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    [[NSNotificationCenter defaultCenter] removeObserver:self                                                    name:UIKeyboardWillHideNotification                                                  object:nil];    [[NSNotificationCenter defaultCenter] removeObserver:self                                                    name:UIKeyboardDidShowNotification                                                  object:nil];}