小编Jac*_*unt的帖子

我在IB中有一个UIStackView，并且正在viewDidLoad中删除和添加子视图。删除子视图时会崩溃。

[self.headerStackView.arrangedSubviews each:^(UIView *subview) {
    [self.headerStackView removeArrangedSubview:subview];
    [subview removeConstraints:subview.constraints];
    [subview removeFromSuperview];
}];

调试器：

2016-11-29 12:35:18.568137 RocheUnregulated[2211:937474] [LayoutConstraints] View hierarchy unprepared for constraint.
Constraint: <NSLayoutConstraint:0x17429ec80 'UISV-spacing' H:[EntryItemInfoView:0x10fe10840]-(15)-[EntryItemInfoView:0x10fd85e50]   (active)>
Container hierarchy: 
<UIStackView: 0x10fe14160; frame = (125 12; 183 51); opaque = NO; autoresize = RM+BM; layer = <CATransformLayer: 0x1700351c0>>
 | <EntryItemInfoView: 0x10fd85e50; frame = (66 0; 51 51); autoresize = RM+BM; layer = <CALayer: 0x1702308e0>>
 |    | <UIStackView: 0x10fd86570; frame = (10 10; 31 31); opaque = NO; autoresize = RM+BM; layer …