前沿的自动布局约束

Question

我有3个UIViews-view1，view2，view3。我在情节提要中设置了约束，如下所示：

1. view1.leading = safeArea。Lead + 0（约束1作为IBOutlet），
2. view2.leading = view1。Lead，
3. view3.leading = view2.lead

接下来，我在代码中更改constraint1中的常量。我希望view1，view2，view3在view1.leading更改时自动重新对齐。但是相反，我得到了自动布局错误：

 [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:0x283317a70 UIView:0x10321f7d0.leading == UILayoutGuide:0x28290ddc0'UIViewSafeAreaLayoutGuide'.leading   (active)>",
"<NSLayoutConstraint:0x283316bc0 UIView:0x10321f7d0.leading == UILayoutGuide:0x28290ddc0'UIViewSafeAreaLayoutGuide'.leading + 5   (active)>"
 )

  Will attempt to recover by breaking constraint 
   <NSLayoutConstraint:0x283316bc0 UIView:0x10321f7d0.leading == UILayoutGuide:0x28290ddc0'UIViewSafeAreaLayoutGuide'.leading + 5   (active)>

我在做什么错了？

Answer 1

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该错误似乎使您对view1有2个前导约束，其中一个约束现在具有5的常数。