大家在使用自動(dòng)布局的時(shí)候，經(jīng)常一不小心會(huì)出現(xiàn)約束警告，log如下：

[LayoutConstraints] 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. 
(
    "<NSLayoutConstraint:0x283bcbca0 UIView: 0x283badc20.height == 40>",
    "<NSLayoutConstraint:0x283bcbf20 UIView: 0x283badc20.top == UITableViewCellContentView:0x1062e0460.top>",
    "<NSLayoutConstraint:0x283bd74d0 UITableViewCellContentView:0x1062e0460.bottom == UIView:0x1062e0600.bottom>",
    "<NSLayoutConstraint:0x283bb14a0 UITableViewCellContentView:0x1062e0460.height == 1>"
)

我們需要知道哪些對(duì)象的約束出現(xiàn)了問(wèn)題，可以在當(dāng)前界面出現(xiàn)時(shí)，

1. 點(diǎn)擊xcode底部的pause program execution按鈕，暫停程序的執(zhí)行
   
   image.png

2.輸入lldb命令：p (id(0x283badc20))->isa,其中0x283badc20就是對(duì)象地址，輸出結(jié)果為對(duì)應(yīng)的類(lèi)信息：

(lldb) p (id(0x283badc20))->isa
(Class) $18 = NeighborTest.XLHomePageSectionHeaderView