ios - 由于未捕获的异常 'NSGenericException' 而终止应用程序，原因 : '*** Collection <__NSSetM...> was mutated while being enumerated.'

Question

我不明白问题所在，但我猜是 Storyboard 中的问题(在我的限制下，因为有时对象不在它们必须在的位置)。

* 由于未捕获的异常“NSGenericException”而终止应用程序，原因:“*

Collection <__NSSetM: 0x7fae0b5e6900> was mutated while being enumerated.'
*** First throw call stack:

 - (
    0   CoreFoundation   __exceptionPreprocess + 165

    1   libobjc.A.dylib  objc_exception_throw + 45

    2   CoreFoundation __NSFastEnumerationMutationHandler + 132

    3   Foundation  -[NSISEngine substituteOutAllOccurencesOfBodyVar:withExpression:] + 336

    4   Foundation -[NSISEngine pivotToMakeBodyVar:newHeadOfRowWithHead:andDropRow:] + 330

    5   Foundation   -[NSISEngine minimizeConstantInObjectiveRowWithHead:] + 314

    6   Foundation  -[NSISEngine tryUsingArtificialVariableToAddConstraintWithMarker:rowBody:usingInfeasibilityHandlingBehavior:mutuallyExclusiveConstraints:] + 285

    7   Foundation  -[NSISEngine tryToAddConstraintWithMarker:expression:integralizationAdjustment:mutuallyExclusiveConstraints:] + 691

    8   Foundation   -[NSLayoutConstraint _addLoweredExpression:toEngine:integralizationAdjustment:lastLoweredConstantWasRounded:mutuallyExclusiveConstraints:] + 275

    9   Foundation   -[NSLayoutConstraint _addToEngine:integralizationAdjustment:mutuallyExclusiveConstraints:] + 220

    10  UIKit  -[UIView(UIConstraintBasedLayout) _layoutEngine_didAddLayoutConstraint:roundingAdjustment:mutuallyExclusiveConstraints:] + 411

    11  UIKit -[UIView(UIConstraintBasedLayout) _tryToAddConstraintWithoutUpdatingConstraintsArray:roundingAdjustment:mutuallyExclusiveConstraints:] + 30

    12  UIKit [UIView(UIConstraintBasedLayout) _tryToAddConstraint:roundingAdjustment:mutuallyExclusiveConstraints:] + 243

    13  UIKit -[UIView(UIConstraintBasedLayout) addConstraints:]_block_invoke + 188

    14  Foundation [NSISEngine withBehaviors:performModifications:] + 155

    15  UIKit  [UIView(UIConstraintBasedLayout) addConstraints:] + 263

    16  UIKit-[UIView _setTraitStorageConstraints:] + 794

Answer 1

这不是自动布局的问题。您正在使用数组或字典或某些 NSSet 对象，这些对象在枚举(从中读取值)的同时被突变(值被添加到其中)。

这个问题主要出现在填充数组之类的东西然后重新加载 UITableView 或 UICollectionView

时