ios - 无法同时满足约束 - Swift

Question

总结:我刚刚完成自动布局，当我运行它时，它们都被挤压在一起。然后我查看命令提示符并显示上面的错误。我试过用谷歌搜索它，但它只显示了 Obj-C 的解决方案，而我是在 Swift 中做的。我该如何解决这个自动布局问题？

错误:

2014-10-20 00:07:41.102 Fraction Calculator[74247:6698760] 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:0x7c440f10 V:[UIButton:0x7c440db0'Divide It!'(30)]>",
    "<NSLayoutConstraint:0x7af7bdb0 V:[UIImageView:0x7af7bae0(8)]>",
    "<NSLayoutConstraint:0x7ae928b0 V:[UITextField:0x7ae952d0(30)]>",
    "<NSLayoutConstraint:0x7ae97110 V:[UITextField:0x7ae96f70(30)]>",
    "<NSLayoutConstraint:0x7ae97eb0 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...'(48)]>",
    "<NSLayoutConstraint:0x7ae99cd0 V:[_UILayoutGuide:0x7ae990c0]-(0)-[UILabel:0x7ae97d70'Enter Your Fraction To Be...']>",
    "<NSLayoutConstraint:0x7ae9a000 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...']-(41)-[UITextField:0x7ae96f70]>",
    "<NSLayoutConstraint:0x7ae9a090 V:[UITextField:0x7ae96f70]-(14)-[UIImageView:0x7af7bae0]>",
    "<NSLayoutConstraint:0x7ae9a150 V:[UIImageView:0x7af7bae0]-(13)-[UITextField:0x7ae952d0]>",
    "<NSLayoutConstraint:0x7ae9a270 V:[UITextField:0x7ae952d0]-(59)-[UIButton:0x7c440db0'Divide It!']>",
    "<NSLayoutConstraint:0x7ae9a2a0 V:[UIButton:0x7c440db0'Divide It!']-(50)-[UILabel:0x7ae98df0]>",
    "<NSLayoutConstraint:0x7ae9a300 V:[UILabel:0x7ae98df0]-(166)-[_UILayoutGuide:0x7ae99680]>",
    "<_UILayoutSupportConstraint:0x7c441e80 V:[_UILayoutGuide:0x7ae990c0(20)]>",
    "<_UILayoutSupportConstraint:0x7c441770 V:|-(0)-[_UILayoutGuide:0x7ae990c0]   (Names: '|':UIView:0x7af7abc0 )>",
    "<_UILayoutSupportConstraint:0x7c443610 V:[_UILayoutGuide:0x7ae99680(0)]>",
    "<_UILayoutSupportConstraint:0x7c4429d0 _UILayoutGuide:0x7ae99680.bottom == UIView:0x7af7abc0.bottom>",
    "<NSLayoutConstraint:0x7c44acf0 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7af7abc0(480)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7ae97eb0 V:[UILabel:0x7ae97d70'Enter Your Fraction To Be...'(48)]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

我的约束形象 https://www.dropbox.com/s/1l3ys9k7bdr8qrk/Screenshot%202014-10-20%2021.08.47.png?dl=0我的 iPhone 4 预览图 https://www.dropbox.com/s/7uoulzppalex2r8/Screenshot%202014-10-20%2021.09.48.png?dl=0模拟器中 iPhone 4 的图像 https://www.dropbox.com/s/c1qedgoytcnetri/iOS%20Simulator%20Screen%20Shot%20Oct%2020%2C%202014%2C%209.10.03%20PM.png?dl=0

如果你们有任何问题或需要澄清，请在下方评论

Answer 1

仅通过查看您发布的错误来跟踪哪个是不良约束会有点困难。但是我可以给出一般规则或在使用自动布局或一般约束时要记住的事情，

• 更喜欢在 XIB/ Storyboard中设置约束。当你设置它们时，它会告诉你到底哪里出错了。除非特殊情况，否则您几乎可以在界面构建器中执行所有操作。
• 始终设置相对于周围 View 的约束，尽量不要将所有内容固定到 super View
• 尽可能使用纵横比限制。
• 尝试使用 View 的内在约束大小，避免设置固定的宽度/高度。
• 请记住，当您设置太多约束时，您总会遇到您所面临的那种错误。所以总是认为约束“刚好”可以在运行时找出它的框架。不多也不少，刚好够用。
• 利用不等式约束，它们非常有用。也不要忘记您有拥抱优先级和抗压优先级。

在您的错误中，我看到许多具有固定大小的约束，当您对这些 View 设置间距约束时，它们会产生干扰。所以从头开始，保留我提到的要点并删除不需要的约束。

引用资料，

• Auto layout Programming Guide
• Guide for Debugging Auto layout issues
• Objc issue
• Raywenderlich Guide
• Some Tips