`attemptRecovery(fromError:optionIndex:)` not found on super of Swift subclass of NSDocument
`attemptRecovery(fromError:optionIndex:)` not found on super of Swift subclass of NSDocument
我有一个 objC NSDocument 子类，它本身是 Swift 版本的子类。 ObjC版本调用BOOL result=[self attemptRecoveryFromError:error optionIndex:recoveryOptionIndex];，由Swift子类实现
从Swift子类开始，对于某些错误，调用super如下：
guard let (error as NSError).domain == "someDomain" else {
return super.attemptRecovery(fromError: error, optionIndex: recoveryOptionIndex)
}
该方法不是ObjC子类实现的，应该是NSObject实现的，但是在运行时出现如下错误：
-[App.AppDocument attemptRecoveryFromError:optionIndex:]: unrecognized selector sent to instance 0x60000350d340
为什么找不到方法？它可能与不一定是 NSError 的错误类型有关吗？
attemptRecoveryFromError:optionIndex: 是非正式协议 NSErrorRecoveryAttempting 的一种方法，未被 NSObject 实现，参见 Formal and Informal Protocols
An informal protocol is a category on NSObject, which implicitly makes almost all objects adopters of the protocol. (A category is a language feature that enables you to add methods to a class without subclassing it.) Implementation of the methods in an informal protocol is optional. Before invoking a method, the calling object checks to see whether the target object implements it. Until optional protocol methods were introduced in Objective-C 2.0, informal protocols were essential to the way Foundation and AppKit classes implemented delegation.
更多信息：Error Recovery。
我有一个 objC NSDocument 子类，它本身是 Swift 版本的子类。 ObjC版本调用BOOL result=[self attemptRecoveryFromError:error optionIndex:recoveryOptionIndex];，由Swift子类实现
从Swift子类开始，对于某些错误，调用super如下：
guard let (error as NSError).domain == "someDomain" else {
return super.attemptRecovery(fromError: error, optionIndex: recoveryOptionIndex)
}
该方法不是ObjC子类实现的，应该是NSObject实现的，但是在运行时出现如下错误：
-[App.AppDocument attemptRecoveryFromError:optionIndex:]: unrecognized selector sent to instance 0x60000350d340
为什么找不到方法？它可能与不一定是 NSError 的错误类型有关吗？
attemptRecoveryFromError:optionIndex: 是非正式协议 NSErrorRecoveryAttempting 的一种方法，未被 NSObject 实现，参见 Formal and Informal Protocols
An informal protocol is a category on NSObject, which implicitly makes almost all objects adopters of the protocol. (A category is a language feature that enables you to add methods to a class without subclassing it.) Implementation of the methods in an informal protocol is optional. Before invoking a method, the calling object checks to see whether the target object implements it. Until optional protocol methods were introduced in Objective-C 2.0, informal protocols were essential to the way Foundation and AppKit classes implemented delegation.
更多信息：Error Recovery。