前沿的自动布局约束

Question

我有 3 个 UIView——view1、view2、view3。我在故事板中设置约束如下：

view1.leading = safeArea.leading + 0（约束 1 作为 IBOutlet），
view2.leading = view1.leading,
view3.leading = view2.leading

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)>

我做错了什么？

Answer 1

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该错误看起来像您在 view1 上有 2 个主要约束，其中一个现在的常数为 5。

前沿的自动布局约束

Autolayout constraints for leading edges

storyboard

uiview

ios

autolayout

ios-autolayout