iOS约束冲突警告解决办法

在开发过程中经常会遇到页面显示正常，但依然还有冲突警告。
通常的原因有2个。

一、cell 中的约束冲突

在这种情况下，在 xcode 的控制台打印出得信息当中会单独拎出一条约束。
Will attempt to recover by breaking constraint 下面那一条

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. 
(
    "<SnapKit.LayoutConstraint:0x6040002a08a0@ChoiceArticleCell.swift#182 UIImageView:0x7fae99d49240.left == UIView:0x7fae99d55e70.left>",
    "<SnapKit.LayoutConstraint:0x6040002a0900@ChoiceArticleCell.swift#182 UIImageView:0x7fae99d49240.top == UIView:0x7fae99d55e70.top>",
    "<SnapKit.LayoutConstraint:0x6040002a0960@ChoiceArticleCell.swift#182 UIImageView:0x7fae99d49240.right == UIView:0x7fae99d55e70.right>",
    "<SnapKit.LayoutConstraint:0x6040002a09c0@ChoiceArticleCell.swift#182 UIImageView:0x7fae99d49240.bottom == UIView:0x7fae99d55e70.bottom>"
)

Will attempt to recover by breaking constraint 
<SnapKit.LayoutConstraint:0x6040002a0a20@ChoiceArticleCell.swift#183 UIImageView:0x7fae99d49240.height == UIImageView:0x7fae99d49240.width * 0.425531923770905>

解决办法就是：将这条约束的 优先级降低。约束默认的优先级是1000。

make.height.equalTo(cover.snp.width).multipliedBy(1/2.35).priority(999)

二、普通view里面 会出现 约束冲突

这种情况 通常是view的 translatesAutoresizingMaskIntoConstraints属性 导致
将其改为 false 可以解决问题
针对 view
如果使用 autulayout 就将 translatesAutoresizingMaskIntoConstraints 设为 false
如果不使用 autulayout 就将 translatesAutoresizingMaskIntoConstraints 设为 true

self.translatesAutoresizingMaskIntoConstraints = false

在 tableview 的 header or footerview 使用约束的 view
该 view 的 translatesAutoresizingMaskIntoConstraints 属性需要设置为 true