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# ExceptionHandling Constants

## Topics

### Constants

[`let NSStackTraceKey: String`](/documentation/ExceptionHandling/NSStackTraceKey)

The key for fetching the stack trace (an <doc://com.apple.documentation/documentation/Foundation/NSString>
object) in the <doc://com.apple.documentation/documentation/Foundation/NSException/userInfo-swift.property>
dictionary of the <doc://com.apple.documentation/documentation/Foundation/NSException>
object passed into one of the delegate methods described in <doc://com.apple.documentation/documentation/ExceptionHandling/nsexceptionhandlerdelegate>.

[`let NSUncaughtRuntimeErrorException: String`](/documentation/ExceptionHandling/NSUncaughtRuntimeErrorException)

Identifies an Objective-C runtime error.

[`let NSUncaughtSystemExceptionException: String`](/documentation/ExceptionHandling/NSUncaughtSystemExceptionException)

Identifies an uncaught system exception.

### Macros

[`#define EXCEPTIONHANDLING_EXPORT`](/documentation/ExceptionHandling/EXCEPTIONHANDLING_EXPORT)

[`#define EXCEPTIONHANDLING_IMPORT`](/documentation/ExceptionHandling/EXCEPTIONHANDLING_IMPORT)


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