What is the meaning of the errors related to expected type before and after -> in Core data's NSAsynchronousFetchRequest?

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The "expected type before ->" error in Core Data's NSAsynchronousFetchRequest typically occurs when the input parameter type of the completion block is incorrect or does not match the expected type. This error indicates that the compiler expected a specific type before the -> symbol, which is usually the type of the return value of the completion block.

On the other hand, the "expected type after ->" error usually occurs when the return type of the completion block is incorrect or does not match the expected type specified in the NSAsynchronousFetchRequest. This error indicates that the compiler expected a specific type after the -> symbol, which is usually the return type of the completion block.

To resolve these errors, you should ensure that the input and output types of the completion block match the expected types specified by the NSAsynchronousFetchRequest.