Question

有时我会不断收到这样的错误 - 没有暗示TextView或Button的含义：

    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:0x11d748d0 V:[UITextView:0xc1bb000(65)]>",
    "<NSLayoutConstraint:0x11d77620 V:[UIButton:0x11d71cf0(44)]>",
    "<NSLayoutConstraint:0x11d7be30 V:[UIButton:0x11d79e70(43)]>",
    "<NSLayoutConstraint:0xa1980d0 V:|-(134)-[UITextView:0xc1bb000]   (Names: '|':UIView:0xa1afba0 )>",
    "<NSLayoutConstraint:0xa199ed0 UITextView:0xc1bb000.centerY == UIButton:0x11d71cf0.centerY>",
    "<NSLayoutConstraint:0xa199e50 V:[UIButton:0x11d79e70]-(61)-[UIButton:0x11d71cf0]>",
    "<NSLayoutConstraint:0xa199cb0 V:|-(40)-[UIButton:0x11d79e70]   (Names: '|':UIView:0xa1afba0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x11d748d0 V:[UITextView:0xc1bb000(65)]>

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.

有没有办法在代码中识别导致崩溃的约束？

案文：

  Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x11d748d0 V:[UITextView:0xc1bb000(65)]>

遗憾的是没有多大帮助，因为我不知道这在代码中是哪个约束

Answer 1

你是这样读的：

<NSLayoutConstraint:0x11d748d0 V:    [UITextView:0xc1bb000(65)]>
 ^ Constraint type  ^ Address  ^Axis ^Description in VFL
                      (of constraint)

所以这是一个强制使textview高达65分的约束。在那里你还有一个约束将这个文本视图固定在其超级视图的上边缘134点：

<NSLayoutConstraint:0xa1980d0 V:|-(134)-[UITextView:0xc1bb000]   (Names: '|':UIView:0xa1afba0 )>

将文本视图的Y中心固定到按钮的Y中心的约束：

<NSLayoutConstraint:0xa199ed0 UITextView:0xc1bb000.centerY == UIButton:0x11d71cf0.centerY>

一个约束将按钮固定到特定的垂直位置：

<NSLayoutConstraint:0xa199e50 V:[UIButton:0x11d79e70]-(61)-[UIButton:0x11d71cf0]>

您可能不希望所有这些限制。这里有两个约束，它们试图垂直定位文本视图（基于按钮，并基于超视图顶部的绝对间距）。

在应用中的某个位置，您必须拥有包含文本字段和两个按钮的视图。如果你打破所有例外，你可以注销日志中给出的各种地址，如果你不确定，可以找出超级视图等，但希望你能够从中解决这个问题。

有时将日志复制到文本编辑器并使用单词查找/替换地址以便于阅读更有帮助。

如何找到崩溃约束？

1 个答案: