Member variable Error():operation Foundation
Contains a description of the operation in which an error occurred.
This instance variable contains a character string which describes the operation that caused the error. For errors associated with operators and functions, the character string contains the name of the operator or function. For errors associated with undeclared variables or functions, the character string contains the name of the variables or functions. If the instance variable contains a null string (""), no description of the failed operation was provided by the subsystem in which the error occurred.
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