Provide converters to and from NSString* in sys_string_conversions

Review URL: http://codereview.chromium.org/6355

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@3050 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 37 insertions, 0 deletions

diff --git a/base/foundation_utils_mac.h b/base/foundation_utils_mac.h
new file mode 100644
index 0000000..64ebeda
--- /dev/null
+++ b/base/foundation_utils_mac.h
@@ -0,0 +1,37 @@
+// Copyright (c) 2008 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_FOUNDATION_UTILS_MAC_H_
+#define BASE_FOUNDATION_UTILS_MAC_H_
+
+#include <CoreFoundation/CoreFoundation.h>
+#import <Foundation/Foundation.h>
+
+// CFTypeRefToNSObjectAutorelease transfers ownership of a Core Foundation
+// object (one derived from CFTypeRef) to the Foundation memory management
+// system.  In a traditional managed-memory environment, cf_object is
+// autoreleased and returned as an NSObject.  In a garbage-collected
+// environment, cf_object is marked as eligible for garbage collection.
+//
+// This function should only be used to convert a concrete CFTypeRef type to
+// its equivalent "toll-free bridged" NSObject subclass, for example,
+// converting a CFStringRef to NSString.
+//
+// By calling this function, callers relinquish any ownership claim to
+// cf_object.  In a managed-memory environment, the object's ownership will be
+// managed by the innermost NSAutoreleasePool, so after this function returns,
+// callers should not assume that cf_object is valid any longer than the
+// returned NSObject.
+static inline id CFTypeRefToNSObjectAutorelease(CFTypeRef cf_object) {
+  // When GC is on, NSMakeCollectable marks cf_object for GC and autorelease
+  // is a no-op.
+  //
+  // In the traditional GC-less environment, NSMakeCollectable is a no-op,
+  // and cf_object is autoreleased, balancing out the caller's ownership claim.
+  //
+  // NSMakeCollectable returns nil when used on a NULL object.
+  return [NSMakeCollectable(cf_object) autorelease];
+}
+
+#endif  // BASE_FOUNDATION_UTILS_MAC_H_