以编程方式将约束添加到 ViewControllerCells答案

【问题标题】：Add Constraints programmatically to ViewControllerCells以编程方式将约束添加到 ViewControllerCells
【发布时间】：2017-04-22 20:24:12
【问题描述】：

使用 CollectionViewCells 创建一个“卡片式”菜单，我需要单元格在 |-----| 之间具有相同的空间任何屏幕尺寸。

我能够做到这一点：

addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-15-[v0]-15-|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": appsCollectionView]))

addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": appsCollectionView]))

我将屏幕两侧的边距设置为 15，但每当我在更大的屏幕上加载应用程序时，两者之间的空间也会发生变化。

我试过用：

appsCollectionView.leadingAnchor.constraint(equalTo: trailingAnchor).isActive = true

但我得到了这个日志：

2016-12-07 16:51:14.902586 AppStoreClone[8843:206635] [LayoutConstraints] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x608000283fc0 H:[UICollectionView:0x7f8172010200]-(15)-|   (active, names: '|':AppStoreClone.CategoryCell:0x7f8173309710 )>",
    "<NSLayoutConstraint:0x608000284100 H:[AppStoreClone.CategoryCell:0x7f8173309710]-(0)-[UICollectionView:0x7f8172010200]   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x608000284100 H:[AppStoreClone.CategoryCell:0x7f8173309710]-(0)-[UICollectionView:0x7f8172010200]   (active)>

【问题讨论】：

标签： ios swift constraints nslayoutconstraint