通过代码新增和修改 NSLayoutConstraint

最新推荐文章于 2022-11-27 15:57:55 发布

原创最新推荐文章于 2022-11-27 15:57:55 发布 · 338 阅读

0 ·

CC 4.0 BY-SA版权

本文详细介绍了如何在Swift中通过调整NSLayoutConstraint的常量值来动态改变视图的高度，实现瀑布流布局中item的动态加载效果。文中提供了具体的代码示例，包括如何添加约束、更新约束常量以及带有动画效果的布局更新。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

今天因为要弄一个瀑布流里面item的动态加载，

所以考虑把里面的一些空间的高度设成0从而实现“隐藏”效果

网上对这类修改是关联 NSLayoutConstraint

然后设置对应的constant

下面是网上的答案，但是注意了，要用父类layoutIfNeeded()来重新布局

0 down vote

If you are adding constraint programatically like this:

var constraintButton = NSLayoutConstraint (item: buttonPlay,                                            attribute: NSLayoutAttribute.Bottom,                                            relatedBy: NSLayoutRelation.Equal,                                            toItem: self.view,                                            attribute: NSLayoutAttribute.Bottom,                                            multiplier: 1,                                           constant: 0)// Add the constraint to the viewself.view.addConstraint(constraintButton)

Then you can update it this way:

self.constraintButton.constant = 50self.view.layoutIfNeeded()

And if you want that with animation you can do it this way:

self.view.layoutIfNeeded()UIView.animateWithDuration(1, animations: {    self.constraintButton.constant = 50    self.view.layoutIfNeeded()})

0 down vote

If you are adding constraint programatically like this:

var constraintButton = NSLayoutConstraint (item: buttonPlay,                                            attribute: NSLayoutAttribute.Bottom,                                            relatedBy: NSLayoutRelation.Equal,                                            toItem: self.view,                                            attribute: NSLayoutAttribute.Bottom,                                            multiplier: 1,                                           constant: 0)// Add the constraint to the viewself.view.addConstraint(constraintButton)

Then you can update it this way:

self.constraintButton.constant = 50self.view.layoutIfNeeded()

And if you want that with animation you can do it this way:

self.view.layoutIfNeeded()UIView.animateWithDuration(1, animations: {    self.constraintButton.constant = 50    self.view.layoutIfNeeded()})

再分享一下我老师大神的人工智能教程吧。零基础！通俗易懂！风趣幽默！还带黄段子！希望你也加入到我们人工智能的队伍中来！https://blog.youkuaiyun.com/jiangjunshow

通过代码 新增 和 修改 NSLayoutConstraint

通过代码新增和修改 NSLayoutConstraint