我有一个非常基本的警报视图
<button>Normal Button</button>
<button class='imgButton'>Image Button</button>如果我评论设置UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Exit" message:@"Please enter the password." delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK", nil];
alertView.tag = 2;
alertView.alertViewStyle = UIAlertViewStyleSecureTextInput;
[alertView textFieldAtIndex:0].delegate = self;
[alertView show];
它可以正常工作，但是如果我离开时我在尝试显示警报视图时遇到了崩溃：
UIAlertViewStyleSecureTextInput我很肯定我没有修改Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The layout constraints still need update after sending -updateConstraints to <_UIKeyboardLayoutAlignmentView: 0x155289c0; frame = (0 0; 0 0); userInteractionEnabled = NO; layer = <CALayer: 0x1558f510>>.
_UIKeyboardLayoutAlignmentView or one of its superclasses may have overridden -updateConstraints without calling super. Or, something may have dirtied layout constraints in the middle of updating them. Both are programming errors.'
的约束，尽管我对布局的其余部分有很多限制。
为什么简单地在UIAlertView上设置文本字段会导致约束崩溃？