前缘的自动布局约束

我有3个ui视图——view1、view2、view3。我在故事板中设置了以下约束:

1. view1.leading=safearea.leading+0(constraint1为iboutlet)
2. view2.leading=视图1.leading,
3. view3.leading=视图2.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。但是我得到的是自动布局错误:

 [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)>

我做错什么了?