AutoLayout，无法同时满足约束 [英] AutoLayout, Unable to simultaneously satisfy constraints

问题描述

刚刚开始学习iOS AutoLayout，接口构建器非常直接，但是当我尝试在代码上存档相同的东西时

  [self.view addConstraints：[NSLayoutConstraint constraintsWithVisualFormat：@H：|  - （== 2） -  [_ nextKeyboardButton]  - （== 2） -  [_ numPadButton]  - （== 2） -  [_ spaceButton]  - （== 2） -  [_ returnButton]  - （== 2） -  | options：0 metrics：0 views：NSDictionaryOfVariableBindings（_nextKeyboardButton，_numPadButton，_spaceButton，_returnButton）]]; 
  

它会引发异常，

无法同时满足约束条件。

 以下列表中的至少一个约束可能是你的一个不想要。试试这个：（1）看看每个约束并试着找出你不期望的东西; （2）找到添加了不需要的约束或约束的代码并修复它。 （注意：如果你看到你不理解的NSAutoresizingMaskLayoutConstraints，请参阅UIView属性translatesAutoresizingMaskIntoConstraints的文档）
（
< NSLayoutConstraint：0x6000000966c0 H：|  - （2） -  [ UIButton：0x7fe4f1d1c760'Next']（名称：'|'：UIInputView：0x7fe4f1f04d00）>，
< NSLayoutConstraint：0x600000096710 H：[UIButton：0x7fe4f1d1c760'Next']  - （2） -  [UIButton： 0x7fe4f1d1d1d0'123']>，
< NSLayoutConstraint：0x600000096760 H：[UIButton：0x7fe4f1d1d1d0'123']  - （2） -  [UIButton：0x7fe4f1d1d6f0'Space']>，
 < NSLayoutConstraint：0x6000000967b0 H：[UIButton：0x7fe4f1d1d6f0'Space']  - （2） -  [UIButton：0x7fe4f1d1d8d0'Return']>，
< NSLayoutConstraint：0x600000096800 H：[UIButton：0x7fe4f1d1d8d0'返回']  - （2） -  |（名称：'|'：UIInputView：0x7fe4f1f04d00）>，
< NSLayoutConstraint：0x600000096e40'UIView-Encapsulated-Layout-Width'H：[UIInputView：0x7fe4f1f04d00（ 0）]>
）
 
将尝试通过违约约束来恢复
< NSLayoutConstraint：0x6000000967b0 H：[UIButton：0x7fe4f1d1d6f0'Space']  - （2） -  [UIButton：0x7fe4f1d1d8d0'Return']> 
  

所有4个按钮.translatesAutoresizingMaskIntoConstraints = NO;

<我想知道出了什么问题？非常感谢帮助:)

仅供参考：我在iOS8 SDK上工作

解决方案

如何找到不可满足约束的最简单方法：

• 为视图中的每个约束设置唯一标识符：

• 为 NSLayoutConstraint 创建简单扩展名：

SWIFT ：

  extension NSLayoutConstraint {
 
覆盖public var description：String {
 let id =标识符？ 
返回id：\（id），常数：\（常数）//你可以在这里打印任何你想要的东西
} 
} 
  

目标-C

  @interface NSLayoutConstraint（Description）
 
 @end 
 
 @implementation NSLayoutConstraint（Description）
 
  - （NSString *）description {
 return [NSString stringWithFormat：@id：％@，constant：％f，self.identifier，self.constant]; 
} 
 
 @end 
  

• 再次构建它，现在你有更多可读输出：

• 一旦你拿到 id ，你可以在你的中轻点点击它查找导航器：

• 并快速找到它：

如何简单修复案例？

• 尝试将优先级更改为 999 用于破坏约束。

请参阅此处的相关答案：无法同时满足约束条件，将尝试通过违反约束来恢复

Just started learning iOS AutoLayout, Interface builder very straight forward, but when I try to archive the same thing on the code

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-(==2)-[_nextKeyboardButton]-(==2)-[_numPadButton]-(==2)-[_spaceButton]-(==2)-[_returnButton]-(==2)-|" options:0 metrics:0 views:NSDictionaryOfVariableBindings(_nextKeyboardButton,_numPadButton,_spaceButton,_returnButton)]];

it raises an exception,

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:0x6000000966c0 H:|-(2)-[UIButton:0x7fe4f1d1c760'Next']   (Names: '|':UIInputView:0x7fe4f1f04d00 )>",
 "<NSLayoutConstraint:0x600000096710 H:[UIButton:0x7fe4f1d1c760'Next']-(2)-[UIButton:0x7fe4f1d1d1d0'123']>",
 "<NSLayoutConstraint:0x600000096760 H:[UIButton:0x7fe4f1d1d1d0'123']-(2)-[UIButton:0x7fe4f1d1d6f0'Space']>",
 "<NSLayoutConstraint:0x6000000967b0 H:[UIButton:0x7fe4f1d1d6f0'Space']-(2)-[UIButton:0x7fe4f1d1d8d0'Return']>",
 "<NSLayoutConstraint:0x600000096800 H:[UIButton:0x7fe4f1d1d8d0'Return']-(2)-|   (Names: '|':UIInputView:0x7fe4f1f04d00 )>",
 "<NSLayoutConstraint:0x600000096e40 'UIView-Encapsulated-Layout-Width' H:[UIInputView:0x7fe4f1f04d00(0)]>"
 )

Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x6000000967b0 H:[UIButton:0x7fe4f1d1d6f0'Space']-(2)-[UIButton:0x7fe4f1d1d8d0'Return']>

All 4 buttons .translatesAutoresizingMaskIntoConstraints = NO;

I wonder what is wrong ? help is really appreciated :)

FYI: I work on iOS8 SDK

解决方案

The easiest way how to find unsatisfiable constraints:

• set unique identifier for every constraint in your view:

• create simple extension for NSLayoutConstraint:

SWIFT:

extension NSLayoutConstraint {

    override public var description: String {
        let id = identifier ?? ""
        return "id: \(id), constant: \(constant)" //you may print whatever you want here
    }
}

OBJECTIVE-C

@interface NSLayoutConstraint (Description)

@end

@implementation NSLayoutConstraint (Description)

-(NSString *)description {
    return [NSString stringWithFormat:@"id: %@, constant: %f", self.identifier, self.constant];
}

@end

• build it once again, and now you have more readable output for you:

• once you got your id you can simple tap it in your Find Navigator:

• and quickly find it:

HOW TO SIMPLE FIX THAT CASE?

• try to change priority to 999 for broken constraint.

See the related answer here: Unable to simultaneously satisfy constraints, will attempt to recover by breaking constraint

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