-[NSMapTable objectEnumerator] returns nil for empty map tables

Originator:prachi
Number:rdar://19893944 Date Originated:
Status:Open Resolved:
Product:Developer Tools Product Version:
Classification: Reproducible:Always
 
Summary:
Sending an NSMapTable -objectEnumerator returns nil for empty map tables instead of an enumerator with no objects. This is unexpected, undocumented, and crashes Swift apps because objectEnumerator is declared as follows in Swift:

func objectEnumerator() -> NSEnumerator

Steps to Reproduce:
(See attached playground for Swift).

1. Create a new NSMapTable instance.
2. Send the instance the -objectEnumerator message before adding any objects to it.

Expected Results:
An NSEnumerator instance with zero objects should be returned. This is what NSDictionary and NSArray do.

Actual Results:
nil is returned.

Version:
Xcode 6.1.1/6A2008a), OS X 10.10.2/14C109

Notes:

Configuration:
This occurs for both iOS and OS X apps.

Comments

Swift playground:

import Cocoa

var mapTable = NSMapTable.strongToStrongObjectsMapTable()

var keyEnumerator = mapTable.keyEnumerator()

var objectEnumerator = mapTable.objectEnumerator()

By prachi at Feb. 19, 2015, 10:09 p.m. (reply...)

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