最近在做ipad的登录注册，测试的时候就点击输入框，结果发现有系统的打印信息，但系统无崩溃。
系统打印信息如下：

2017-05-27 11:39:08.636670+0800 GoGoTalkHD[6324:969512] [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. 
<__NSArrayI 0x60800044e550>(
<NSLayoutConstraint:0x610000092d90 _UIButtonBarStackView:0x7fe40af2c730.width <= 0>,
<NSLayoutConstraint:0x610000092020 UILayoutGuide:0x610000199980.left == _UIButtonBarStackView:0x7fe40af2c730.left + 15>,
<NSLayoutConstraint:0x6100000920c0 _UIButtonBarStackView:0x7fe40af2c730.right == UILayoutGuide:0x610000199980.right + 15>
)


Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6100000920c0 _UIButtonBarStackView:0x7fe40af2c730.right == UILayoutGuide:0x610000199980.right + 15>

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.
2017-05-27 11:39:08.638155+0800 GoGoTalkHD[6324:969512] [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. 
<__NSArrayI 0x61800005d640>(
<NSLayoutConstraint:0x610000092de0 _UIButtonBarStackView:0x7fe40af3b480.width <= 0>,
<NSLayoutConstraint:0x610000092660 UILayoutGuide:0x61000019a000.left == _UIButtonBarStackView:0x7fe40af3b480.left + 15>,
<NSLayoutConstraint:0x610000092700 _UIButtonBarStackView:0x7fe40af3b480.right == UILayoutGuide:0x61000019a000.right + 15>
)


Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x610000092700 _UIButtonBarStackView:0x7fe40af3b480.right == UILayoutGuide:0x61000019a000.right + 15>

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.

直观显示.png

百度资料之后，以为是约束问题，查找了自己的代码之后，还是无法消除。继续查找之后发现说是键盘类型切换的问题。就注销了代码

self.phoneAccountField.keyboardType = UIKeyboardTypeNumberPad;
self.passwordField.secureTextEntry = YES;

发现问题消失。具体的未深究。估计这个是苹果的小bug吧。