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# File Property Keys

Keys that apply to properties of files.

## Topics

### Constants

[`let kCFURLFileAllocatedSizeKey: CFString!`](/documentation/CoreFoundation/kCFURLFileAllocatedSizeKey)

Key for the total size allocated on disk for the file, returned as an `CFNumber` object.

[`let kCFURLFileSizeKey: CFString!`](/documentation/CoreFoundation/kCFURLFileSizeKey)

Key for the file’s size in bytes, returned as a `CFNumber` object.

[`let kCFURLIsAliasFileKey: CFString!`](/documentation/CoreFoundation/kCFURLIsAliasFileKey)

Key for determining whether the file is an alias, returned as a `CFBoolean` object.

[`let kCFURLIsMountTriggerKey: CFString!`](/documentation/CoreFoundation/kCFURLIsMountTriggerKey)

Key for determining whether the URL is a file system trigger directory, returned as a `CFBoolean` object. Traversing or opening a file system trigger directory causes an attempt to mount a file system on the directory.

[`let kCFURLTotalFileAllocatedSizeKey: CFString!`](/documentation/CoreFoundation/kCFURLTotalFileAllocatedSizeKey)

Key for the total allocated size of the file in bytes, returned as a `CFNumber` object. This includes the size of any file metadata.

[`let kCFURLTotalFileSizeKey: CFString!`](/documentation/CoreFoundation/kCFURLTotalFileSizeKey)

Key for the total displayable size of the file in bytes, returned as a `CFNumber` object. This includes the size of any file metadata.


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