iOS開發——使用Autolayout彈出鍵盤

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參考：

http://segmentfault.com/q/1010000002420050

http://blog.csdn.net/qq448631961/article/details/40345653

 

思路：

在整個View下面塞進一個高度為0的視圖(使用低優先順序約束)，當鍵盤改變時改變該View的高度即可。

 

constraint 有一個唯一可以修改的屬性 constant，我承認它的名字確實很具有迷惑性。。。
以題主提到的高度問題為例，可以儲存這個高度 constraint 的引用，在鍵盤出現和收合時

- (void)keyboardDidShowNotification
{
    self.viewHeightConstraint.constant = 100.f;
    [self.myView layoutIfNeed];
}

- (void)keyboardDidHideNotification
{
    self.viewHeightConstraint.constant = 300.f;
    [self.myView layoutIfNeed];
}

 

 

My Code：

註冊通知：

   1:   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillChangeFrameNotification object:nil];

 

 

約束

@property (nonatomic,strong) NSLayoutConstraint* keyboardConstraint;

 

初始為0

   1:  self.keyboardConstraint = [NSLayoutConstraint constraintWithItem:self.keyboardView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:0];

 

 

   1:  - (void)keyboardWillShow:(NSNotification *)notification{

   2:      CGRect kbFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];

   3:      self.keyboardConstraint.constant = kbFrame.size.height;

   4:      [self.view addConstraint:self.keyboardConstraint];

   5:      //    [self.inputView needsUpdateConstraints];

   6:      [self.view setNeedsLayout];

   7:      [self.view layoutIfNeeded];

   8:      if (self.messages.count > 0){

   9:      NSIndexPath *idxP = [NSIndexPath indexPathForRow:(self.messages.count - 1) inSection:0];

  10:          [self.tableView scrollToRowAtIndexPath:idxP atScrollPosition:UITableViewScrollPositionBottom animated:YES];}

  11:      

  12:  }

  13:   

  14:  - (void)keyboardWillHidden{

  15:      

  16:      [self.view endEditing:YES];

  17:      [UIView animateWithDuration:0.25 animations:^{

  18:          //        self.keyboardConstraint.constant = 0;

  19:          self.keyboardConstraint.constant = 0;

  20:          //        [self.view removeConstraint:self.keyboardConstraint];

  21:          [self.view setNeedsLayout];

  22:          [self.view layoutIfNeeded];

  23:      }];

  24:      

  25:  }

iOS開發——使用Autolayout彈出鍵盤