ios - UIView animateWithDuration 不改变 UIView 的框架

Question

我正在尝试实现一个下拉 View ，当用户按下按钮时，该 View 将向下移动，一旦用户按下同一按钮，该 View 将再次上升到上方。为此，我使用以下代码:

[UIView animateWithDuration:0.25f animations:^{
        self.dropdownView.frame =
        CGRectMake(self.dropdownView.frame.origin.x,
                   self.dropdownView.frame.origin.y+42,
                   self.dropdownView.frame.size.width,
                   self.dropdownView.frame.size.height);
    }
                     completion:^(BOOL finished){
        NSLog(@"%@",self.dropdownView);
    }];

我在这里尝试的是将原点向下移动 42 点以创建下拉式动画。在向上移动的情况下，我正在使用:

[UIView animateWithDuration:0.25f animations:^{
        self.dropdownView.frame =
        CGRectMake(self.dropdownView.frame.origin.x,
                   self.dropdownView.frame.origin.y-42,
                   self.dropdownView.frame.size.width,
                   self.dropdownView.frame.size.height);
    }
                     completion:^(BOOL finished){
    NSLog(@"%@",self.dropdownView);

    }];

但是，如果我检查日志，下拉 View 的框架不会更新。但是，如果我在另一个具有不同 UI 元素的 VC 中使用相同的代码，则此代码可以正常工作。在这两种情况下，我都在 Storyboard中创建了下拉 View 。代码有什么问题导致它无法正常工作？

编辑

当我在第一个动画之前记录约束时，日志是:

Constraints: (
"<NSIBPrototypingLayoutConstraint:0x7fcb01797460 'IB auto generated at build time for view with fixed frame' H:|-(0)-[UIImageView:0x7fcb01481970](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017c0ac0 'IB auto generated at build time for view with fixed frame' V:|-(0)-[UIImageView:0x7fcb01481970]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017c0b10 'IB auto generated at build time for view with fixed frame' H:[UIImageView:0x7fcb01481970(320)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aa360 'IB auto generated at build time for view with fixed frame' V:[UIImageView:0x7fcb01481970(42)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aa3b0 'IB auto generated at build time for view with fixed frame' H:|-(0)-[UIButton:0x7fcb017e8080](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017824e0 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb017e8080]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01782530 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb017e8080(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb0179fe70 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb017e8080(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb0179fec0 'IB auto generated at build time for view with fixed frame' H:|-(82)-[UIButton:0x7fcb01796ea0](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01776490 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01796ea0]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017764e0 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01796ea0(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017956b0 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01796ea0(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01795700 'IB auto generated at build time for view with fixed frame' H:|-(164)-[UIButton:0x7fcb01699f60](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01795860 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01699f60]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017958b0 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01699f60(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aef40 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01699f60(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aef90 'IB auto generated at build time for view with fixed frame' H:|-(242)-[UIButton:0x7fcb01667610](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017b44b0 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01667610]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017b4500 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01667610(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017bbde0 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01667610(36)]>")

动画完成后的约束日志是:

Constraints: (
"<NSIBPrototypingLayoutConstraint:0x7fcb01797460 'IB auto generated at build time for view with fixed frame' H:|-(0)-[UIImageView:0x7fcb01481970](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017c0ac0 'IB auto generated at build time for view with fixed frame' V:|-(0)-[UIImageView:0x7fcb01481970]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017c0b10 'IB auto generated at build time for view with fixed frame' H:[UIImageView:0x7fcb01481970(320)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aa360 'IB auto generated at build time for view with fixed frame' V:[UIImageView:0x7fcb01481970(42)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aa3b0 'IB auto generated at build time for view with fixed frame' H:|-(0)-[UIButton:0x7fcb017e8080](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017824e0 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb017e8080]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01782530 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb017e8080(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb0179fe70 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb017e8080(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb0179fec0 'IB auto generated at build time for view with fixed frame' H:|-(82)-[UIButton:0x7fcb01796ea0](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01776490 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01796ea0]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017764e0 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01796ea0(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017956b0 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01796ea0(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01795700 'IB auto generated at build time for view with fixed frame' H:|-(164)-[UIButton:0x7fcb01699f60](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb01795860 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01699f60]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017958b0 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01699f60(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aef40 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01699f60(36)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017aef90 'IB auto generated at build time for view with fixed frame' H:|-(242)-[UIButton:0x7fcb01667610](LTR)   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017b44b0 'IB auto generated at build time for view with fixed frame' V:|-(3)-[UIButton:0x7fcb01667610]   (Names: '|':UIView:0x7fcb014a16b0 )>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017b4500 'IB auto generated at build time for view with fixed frame' H:[UIButton:0x7fcb01667610(79)]>",
"<NSIBPrototypingLayoutConstraint:0x7fcb017bbde0 'IB auto generated at build time for view with fixed frame' V:[UIButton:0x7fcb01667610(36)]>")

编辑2

这就是我想要实现的:这是动画之前的 View 。单击箭头按钮后， View 应如图所示向下移动

在这里，安排 session 和音乐会后是两个按钮，它们是我的下拉 View 的 subview 。他们在那里，甚至在动画之前，但他们在棕色 View 后面，所以他们没有被显示，一旦我按下箭头按钮，他们向下移动并变得可见

Answer 1

当您使用 AutoLayout 时，您无法直接更新应用的 frame 或 center。

它只是行不通。定义框架的约束将覆盖您所做的任何更改，并且它将保持原样。

对于您的动画，您需要设置类似这样的约束...

你可能想设置左间距和右间距而不是固定宽度等...

然后需要将顶部约束存储在属性中...

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

我们可以更改此约束以动画 View 的框架。 NSLayoutConstraint 中唯一可写的部分是 constant 属性。 (讽刺)

无论如何，你的动画代码将是这样的......

self.topConstraint.constant += 42;

[UIView animateWithDuration:0.25f
                 animations:^{
                     [self.view setNeedsLayout];
                 }
                 completion:^(BOOL finished) {
                     NSLog(@"%@",self.dropdownView);
                 }];