以编程方式尝试 NSLayoutContraint 给出“无法同时满足约束”。答案

【问题标题】：Programmatically attempting NSLayoutContraint gives "Unable to simultaneously satisfy constraints."以编程方式尝试 NSLayoutContraint 给出“无法同时满足约束”。
【发布时间】：2013-04-05 00:29:02
【问题描述】：

我似乎在以编程方式为我正在使用的 UITableView 设置约束时遇到了一些问题。我的尝试如下，并尝试了使用translatesAutoresizingMaskIntoConstraints 的所有可能组合。

    self.view.translatesAutoresizingMaskIntoConstraints = NO;
    _tableView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-100-[_tableView]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_tableView)]];

我只是想在 UIViewController 上的 UITableView 的开头和底部添加一个空格。有人可以帮忙吗？

长长的错误如下。

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) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x75c8500 h=-&- v=-&- UITableView:0x799e400.midY == UIView:0x71a4ec0.midY>",
    "<NSLayoutConstraint:0x71a5800 V:[UITableView:0x799e400]-(20)-|   (Names: '|':UIView:0x71a4ec0 )>",
    "<NSLayoutConstraint:0x71a5a60 V:|-(100)-[UITableView:0x799e400]   (Names: '|':UIView:0x71a4ec0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x71a5800 V:[UITableView:0x799e400]-(20)-|   (Names: '|':UIView:0x71a4ec0 )>

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.
2013-04-04 20:06:57.648 New eCard[29731:c07] 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) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x75c8540 h=-&- v=-&- UITableView:0x799e400.height == UIView:0x71a4ec0.height>",
    "<NSAutoresizingMaskLayoutConstraint:0x75c8500 h=-&- v=-&- UITableView:0x799e400.midY == UIView:0x71a4ec0.midY>",
    "<NSLayoutConstraint:0x71a5a60 V:|-(100)-[UITableView:0x799e400]   (Names: '|':UIView:0x71a4ec0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x71a5a60 V:|-(100)-[UITableView:0x799e400]   (Names: '|':UIView:0x71a4ec0 )>

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.
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) 
(
    "<NSAutoresizingMaskLayoutConstraint:0x75c8540 h=-&- v=-&- UITableView:0x799e400.height == UIView:0x71a4ec0.height>",
    "<NSAutoresizingMaskLayoutConstraint:0x75c8500 h=-&- v=-&- UITableView:0x799e400.midY == UIView:0x71a4ec0.midY>",
    "<NSLayoutConstraint:0x71a5800 V:[UITableView:0x799e400]-(20)-|   (Names: '|':UIView:0x71a4ec0 )>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x71a5800 V:[UITableView:0x799e400]-(20)-|   (Names: '|':UIView:0x71a4ec0 )>

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.

【问题讨论】：

您是在 IB 中还是在代码中创建了这个表视图。它表明您在 table view 和 superview 之间有一个 mid-y 约束。
哦，我真的很抱歉我可以发誓我把那部分放在那里。我用过 IB。
如果您使用的是 IB，为什么要在代码中设置约束？当您在 IB 中创建对象时，您会得到 Xcode 放入的约束，它们可能与您添加的约束发生冲突。
有一点我必须能够在我的代码中更改约束。
如果您在 IB 中创建了 tableview，那么不应该有任何 AutoresizingMaskLayoutContraints，因为 IB 将创建正常约束而不是自动调整掩码大小。您的 xib 文件是否设置为使用自动布局？

标签： ios ios6 autolayout

【解决方案1】：

我发现这个关于 UICollectionView 的问题。我想这是开始调试的好点。

UICollectionView Cell + UiLabel with AutoLayout

我尝试过但没有成功的解决方案的其他一些链接： https://blog.safaribooksonline.com/2012/10/27/tip-unsatisfiable-auto-layouts-in-ios-6/ UITableView with autolayout and offset constraints

【讨论】：