动画后

Question

我已经做到这一点，当用户点击文本字段时，视图会略微向上移动，以便在用户键入时字段仍然可见。它工作得很好，但有时在键盘被解除后，而不是返回到原来的位置，视图向下滑得太远（在顶部留下一个小的空白黑条）。有谁知道如何将视图恢复到原来的位置？这是我的代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.


    _userField.returnKeyType = UIReturnKeyDone;
    [_userField setDelegate:self];

    _passField.returnKeyType = UIReturnKeyDone;
    [_passField setDelegate:self];


    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dismissKeyboard)];
    [self.view addGestureRecognizer:tap];
}


- (void)dismissKeyboard
{
    [_userField resignFirstResponder];
    [_passField resignFirstResponder];

}

-(void)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
}

-(void)textFieldDidBeginEditing:(UITextField *)textField
{
    [self animateTextField:textField up:YES];
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{
    [self animateTextField:textField up:NO];
}

    -(void)animateTextField:(UITextField*)textField up:(BOOL)up
    {
        const int movementDistance = -130; // tweak as needed
        const float movementDuration = 0.3f; // tweak as needed

        int movement = (up ? movementDistance : -movementDistance);

        [UIView beginAnimations: @"animateTextField" context: nil];
        [UIView setAnimationBeginsFromCurrentState: YES];
        [UIView setAnimationDuration: movementDuration];
        self.view.frame = CGRectOffset(self.view.frame, 0, movement);
        [UIView commitAnimations];
    }

Answer 1

我建议你改用键盘通知。这样，即使您有多个字段，它也可以工作，您可以使用键盘动画为变化设置动画，并且您将确切知道由于键盘显示您将丢失多少屏幕区域。

首先，在视图控制器中，注册并取消注册通知：

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];
}

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

然后实现触发通知时调用的两个方法：

- (void)keyboardWillShowNotification:(NSNotification *)notification {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:[notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]];
    [UIView setAnimationCurve:(UIViewAnimationCurve)[notification.userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue]];
    [UIView setAnimationBeginsFromCurrentState:YES];
    CGRect keyboardFrame = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
    [self.mainView adjustContentWithKeyboardHeight:keyboardFrame.size.height];
    [UIView commitAnimations];
}

- (void)keyboardWillHideNotification:(NSNotification *)notification {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:[notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue]];
    [UIView setAnimationCurve:(UIViewAnimationCurve)[notification.userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue]];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [self.mainView adjustContentWithKeyboardHeight:0];
    [UIView commitAnimations];
}

最后，在您的视图中实施adjustContentWithKeyboardHeight公共方法。由于在UIView动画中调用该方法，因此所有更改都将进行动画处理。

如果要直接移动视图（将它们全部放在要移动的容器视图中），请将原始Y位置保留在私有属性中，然后从该属性中减去keyboardHeight减去textField下面的剩余空间，并且将其分配回该字段（或根据自己的喜好设置框架）：

    CGFloat offsetY = keyboardHeight - (CGRectGetHeight(self.bounds) - CGRectGetMaxY(self.containerView.frame));
    CGRect containerFrame = self.containerView.frame;
    containerFrame.origin.y = self.containerViewPositionY - offsetY;
    self.containerView.frame = containerFrame;