将 UIView 底部空间约束设置为键盘高度

Question

我是自动布局的忠实粉丝，但一直在 Storyboard 中实现它。

我有一个 UIView，我希望底部空间约束位于键盘结束的位置。

我已经定义了所有的约束，有人可以告诉我如何在代码中为底部空间实现这个约束吗？以及如何根据特定的 iDevice 获取键盘高度的值并将其与约束匹配。

谢谢

Answer 1

像这样取出视图的底部约束

@property (weak, nonatomic) IBOutlet NSLayoutConstraint *constraintContainerBottom;

并使用它

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self setupKeyboard:YES];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [self setupKeyboard:NO];
}

- (void)setupKeyboard:(BOOL)appearing
{
    if (appearing) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    }else{
        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillShowNotification object:nil];
        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
    }
}

- (void)keyboardWillShow:(NSNotification*)notification
{
    CGSize keyboardSize = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    double duration = [[[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    int curve = [[[notification userInfo] objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue];
    [UIView beginAnimations:@"keyboardShown" context:nil];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationCurve:curve];

    self.constraintContainerBottom.constant = keyboardSize.height;
    [self.view layoutIfNeeded];

    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];
}

- (void)keyboardWillHide:(NSNotification*)notification
{
    double duration = [[[notification userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    int curve = [[[notification userInfo] objectForKey:UIKeyboardAnimationCurveUserInfoKey] intValue];
    [UIView beginAnimations:@"keyboardHidden" context:nil];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationCurve:curve];

    self.constraintContainerBottom.constant = 0;
    [self.view layoutIfNeeded];

    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];
}