ios - swift 3 : -[_SwiftValue mergeType]: unrecognized selector sent to instance

Question

每当我在删除或更新记录后尝试保存托管对象上下文时，都会收到“-[_SwiftValue mergeType]: unrecognized selector sent to instance”错误。例如:

context.delete(managedObject)

遵从

context.save()

是的，context.save() 正在 try catch 。

记录插入就好了，但删除会引发异常。堆栈跟踪如下:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_SwiftValue mergeType]: unrecognized selector sent to instance 0x60800005b0f0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010afac34b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010a5f021e objc_exception_throw + 48
    2   CoreFoundation                      0x000000010b01bf34 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x000000010af31c15 ___forwarding___ + 1013
    4   CoreFoundation                      0x000000010af31798 _CF_forwarding_prep_0 + 120
    5   CoreData                            0x000000010aae203a -[NSManagedObjectContext(_NSInternalAdditions) _validateObjects:forOperation:error:exhaustive:forSave:] + 1946
    6   CoreData                            0x000000010aae1836 -[NSManagedObjectContext(_NSInternalAdditions) _validateChangesForSave:] + 422
    7   CoreData                            0x000000010aae1476 -[NSManagedObjectContext(_NSInternalChangeProcessing) _prepareForPushChanges:] + 214
    8   CoreData                            0x000000010aaddeb2 -[NSManagedObjectContext save:] + 562

跟踪在离开我的代码后立即开始。

任何见解都会有所帮助。

Answer 1

当您使用这样的代码来设置合并策略时，您可能会收到此错误:

context.mergePolicy = NSMergePolicyType.mergeByPropertyStoreTrumpMergePolicyType

而是使用这个:

context.mergePolicy = NSMergePolicy(merge: .mergeByPropertyStoreTrumpMergePolicyType)