IOS：键盘出现时将TextField向上移动

Question

我使用以下方法在键盘出现时将视图向上移动，以便键盘不会阻止文本字段。 基本上，我将文本字段嵌入到滚动视图中，并在出现键盘时向上滚动。

// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
    NSDictionary* info = [aNotification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;

    UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
    _scrollView.contentInset = contentInsets;
    _scrollView.scrollIndicatorInsets = contentInsets;

    // If active text field is hidden by keyboard, scroll it so it's visible
    // Your app might not need or want this behavior.
    CGRect aRect = self.view.frame;
    aRect.size.height -= kbSize.height;
    if (!CGRectContainsPoint(aRect, _activeField.frame.origin) ) {
        [_scrollView scrollRectToVisible:_activeField.frame animated:YES];
    }
}

但是，当文本字段已经位于视图的顶部并且不需要向上跳转时，上面的代码将导致其跳出视图。

我记得在某处您可以添加一行来防止这种情况，但我不记得了。 基本上，它将测试文本字段是否已经足够高到足以使键盘无法覆盖它，因此不需要移动视图。

上面代码中的if语句似乎并未筛选出未隐藏文本字段的情况。

有人可以建议一种方法吗？

谢谢。

Answer 1

如果使用自动布局，则应使用约束而不是框架来操纵视图。 您可以根据需要尝试操纵textField的底部间距或查看其超级视图，然后将layoutIfNeeded调用放入动画块中。 您还可以检查底部约束的值是否已经是特定值，或者在UIKeyboardWillHideNotification和UIKeyboardWillShowNotification上传递布尔值（如果是），则约束的值不应更改。 就像是：

-(void)showViewAnimatedly:(BOOL)show{

    if(show){
        [bottomConstraint setConstant:0];
    }else{
        [bottomConstraint setConstant:-160];
    }

    [UIView animateWithDuration:0.3f animations:^{

        [self.view layoutIfNeeded];

    }];
}

我还建议您使用UIKeyboardWillShowNotification而不是UIKeyboardDidShowNotification因为过渡似乎与键盘的出现更加UIKeyboardDidShowNotification 。 UIKeyboardDidShowNotification将在出现键盘后开始过渡。

Answer 2

签出“ IQKeyboardManager”。 它是满足您要求的绝佳控件。 而且您只需要一行代码。 它适用于UITextFields和UITextViews。 它还具有上一个和下一个按钮的选项。 您可以将它作为cocoapod安装在项目中

https://www.cocoacontrols.com/controls/iqkeyboardmanager

Answer 3

它很简单，当需要出现键盘时，可以通过动画更改文本视图或文本字段的y轴坐标。 您可以参考的代码如下---->

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}