Question

我正在移动一些视图以编程方式更改其约束，在某些时候我得到了这个：

2013-11-12 02:26:35.169 App[27290:70b] 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. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x8b43490 V:[UIButton:0x8b43370(44)]>",
    "<NSLayoutConstraint:0x8b413e0 V:|-(0)-[UITableView:0xe1f0200]   (Names: '|':UIView:0x8b46430 )>",
    "<NSLayoutConstraint:0x8b41410 V:[UIButton:0x8b43370]-(0)-|   (Names: '|':UIView:0x8b46430 )>",
    "<NSLayoutConstraint:0x8b41470 V:[UITableView:0xe1f0200]-(0)-[UIButton:0x8b43370]>",
    "<NSLayoutConstraint:0x8b41680 V:|-(220)-[UIView:0x8b46430]   (Names: '|':UIView:0x8b463a0 )>",
    "<NSLayoutConstraint:0x8b444a0 V:[UIView:0x8b46430]-(404)-|   (Names: '|':UIView:0x8b463a0 )>",
    "<NSLayoutConstraint:0x8b445d0 V:[UIView:0x8b463a0]-(0)-|   (Names: '|':FXBlurView:0x8b460c0 )>",
    "<NSLayoutConstraint:0x8b44630 V:|-(0)-[UIView:0x8b463a0]   (Names: '|':FXBlurView:0x8b460c0 )>",
    "<NSLayoutConstraint:0x8b44ce0 V:|-(0)-[FXBlurView:0x8b460c0]   (Names: '|':UIView:0x8b448d0 )>",
    "<NSLayoutConstraint:0x8b44760 V:[FXBlurView:0x8b460c0]-(0)-[_UILayoutGuide:0x8b44790]>",
    "<_UILayoutSupportConstraint:0x8b46790 V:[_UILayoutGuide:0x8b44790(0)]>",
    "<_UILayoutSupportConstraint:0x8b57e40 _UILayoutGuide:0x8b44790.bottom == UIView:0x8b448d0.bottom>",
    "<NSAutoresizingMaskLayoutConstraint:0x8b5aed0 h=--& v=--& V:[UIView:0x8b448d0(568)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x8b43490 V:[UIButton:0x8b43370(44)]>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2013-11-12 02:26:35.170 App[27290:70b] 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. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x8b41680 V:|-(220)-[UIView:0x8b46430]   (Names: '|':UIView:0x8b463a0 )>",
    "<NSLayoutConstraint:0x8b444a0 V:[UIView:0x8b46430]-(404)-|   (Names: '|':UIView:0x8b463a0 )>",
    "<NSLayoutConstraint:0x8b445d0 V:[UIView:0x8b463a0]-(0)-|   (Names: '|':FXBlurView:0x8b460c0 )>",
    "<NSLayoutConstraint:0x8b44630 V:|-(0)-[UIView:0x8b463a0]   (Names: '|':FXBlurView:0x8b460c0 )>",
    "<NSLayoutConstraint:0x8b44ce0 V:|-(0)-[FXBlurView:0x8b460c0]   (Names: '|':UIView:0x8b448d0 )>",
    "<NSLayoutConstraint:0x8b44760 V:[FXBlurView:0x8b460c0]-(0)-[_UILayoutGuide:0x8b44790]>",
    "<_UILayoutSupportConstraint:0x8b46790 V:[_UILayoutGuide:0x8b44790(0)]>",
    "<_UILayoutSupportConstraint:0x8b57e40 _UILayoutGuide:0x8b44790.bottom == UIView:0x8b448d0.bottom>",
    "<NSAutoresizingMaskLayoutConstraint:0x8b5aed0 h=--& v=--& V:[UIView:0x8b448d0(568)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x8b444a0 V:[UIView:0x8b46430]-(404)-|   (Names: '|':UIView:0x8b463a0 )>

Break on objc_exception_throw to catch this in the debugger.

我如何理解导致警告/错误的问题是什么？

我在哪里可以学习如何“阅读”这些警告？

我的意思是例如V:[UIView:0x8b46430]-(404)-|的含义是什么。

Answer 1

N：[UIView的：0x8b46430] - （404） - |

该行转换为：UIView距离它的超级视图底部404pt（在其超级视图内）

NSLayoutConstraint：0x8b41680 V：| - （220） - [UIView：0x8b46430]（名称：'|'：UIView：0x8b463a0） NSLayoutConstraint：0x8b444a0 V：[UIView：0x8b46430] - （404） - | （名称：'|'：UIView：0x8b463a0） NSLayoutConstraint：0x8b445d0 V：[UIView：0x8b463a0] - （0） - | （名称：'|'：FXBlurView：0x8b460c0）

视图0x8b46430与容器UIView的关系为404pt：0x8b463a0，同时将约束设置为0pt到容器FXBlurView：0x8b460c0。

Answer 2

找到解决方案。问题在于您编辑约束的顺序 MATTERS ！

这两个相互矛盾的限制是：

"<NSLayoutConstraint:0x8b41680 V:|-(220)-[UIView:0x8b46430]   (Names: '|':UIView:0x8b463a0 )>",
"<NSLayoutConstraint:0x8b444a0 V:[UIView:0x8b46430]-(404)-|   (Names: '|':UIView:0x8b463a0 )>",

这个UIView的超级视图的顶部空间边距为220 pt，底部空间边距为404 pt，这是错误的，因为它超过了主视图高度（568 pt高）。

错误的代码就是这个：

self.myViewTopMarginCon.constant = $value;
self.myViewBottomMarginCon.constant = $value;

正确的是：

self.myViewBottomMarginCon.constant = $value;
self.myViewTopMarginCon.constant = $value;

无法同时满足约束，如何读取约束

2 个答案: