需求如下:
本人最近在做毕业设计，音乐app，现在遇到问题，想做一个自适应宽度的tableviewcell，里面有三个imageView,imageView的宽度根据屏幕大小自适应，实现imageView的三等分，即imageView宽度自适应，但是imageView的高度要跟宽度是一样高的，即宽高比为1:1。(注明:我的测试图片为宽高比为2:1)。

程序运行如图

确实是实现了我的需求，但是运行的时候控制台会出现很多很多的说我的约束出现错误。

先上一下我设置的约束，这是我的xib图片

好了，现在一个一个看约束,第一个imageView的约束

第二个imageView的约束

第三个imageView的约束

我大概知道最关键的一部分错在哪里，就是我给每个imageView都加了一个约束就是 aspect ratio = 1:1,如果去掉这个约束的话程序运行时控制台是不会说约束错误的，但是去掉了这个约束的话又不是我想要的结果。

下面是控制台的输出
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:0x7faa62826ba0 UIImageView:0x7faa62826d80.width == UIImageView:0x7faa62826d80.height>",
"<NSLayoutConstraint:0x7faa62827510 UIImageView:0x7faa60734960.width == UIImageView:0x7faa628267c0.width>",
"<NSLayoutConstraint:0x7faa62827560 UIImageView:0x7faa60734960.leading == UITableViewCellContentView:0x7faa607347f0.leadingMargin + 2>",
"<NSLayoutConstraint:0x7faa62827650 UIImageView:0x7faa628267c0.width == UIImageView:0x7faa62826d80.width>",
"<NSLayoutConstraint:0x7faa628276a0 H:[UIImageView:0x7faa60734960]-(10)-[UIImageView:0x7faa628267c0]>",
"<NSLayoutConstraint:0x7faa62827790 UIImageView:0x7faa62826d80.top == UITableViewCellContentView:0x7faa607347f0.topMargin + 2>",
"<NSLayoutConstraint:0x7faa628277e0 H:[UIImageView:0x7faa628267c0]-(10)-[UIImageView:0x7faa62826d80]>",
"<NSLayoutConstraint:0x7faa62827880 UITableViewCellContentView:0x7faa607347f0.trailingMargin == UIImageView:0x7faa62826d80.trailing + 2>",
"<NSLayoutConstraint:0x7faa62827830 UITableViewCellContentView:0x7faa607347f0.bottomMargin == UIImageView:0x7faa62826d80.bottom + 1>",
"<NSLayoutConstraint:0x7faa6282b8f0 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x7faa607347f0(112.5)]>",
"<NSLayoutConstraint:0x7faa6282ca60 'UIView-Encapsulated-Layout-Width' H:[UITableViewCellContentView:0x7faa607347f0(320)]>"

)

Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x7faa62826ba0 UIImageView:0x7faa62826d80.width == UIImageView:0x7faa62826d80.height>

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.