On Mar 9, 2008, at 5:58 AM, Trygve Inda wrote:
On 8 Mar '08, at 1:57 PM, Trygve Inda wrote:
Is this expected? Can I rely on it? I will never need to change
dict, but I
am modifying items within a known sub Dictionary.
Don't rely on this; it's entirely possible this behavior could change
in the future, causing your app to throw an exception. Something much
like that happened in 10.4 (I think) — maybe it was the mutability of
collections read from property lists — and broke a bunch of apps.
—Jens
Is it enough then to take the dictionary I get back and do a [dict
mutableCopy]?
Will this cascade down to the "subdicts" (dicts within the top level
dict).
No it won't. mutableCopy only operates on one particular object and
not all its contained objects. While that behavior does sound nice in
some situations, you'd definitely not want that in all situations.
If you need to make modifications to various objects, make sure they
are mutable.
NSDictionary* theImmutableDictionary = [NSDictionary
dictionaryWithObjectsAndKeys:
[NSDictionary dictionaryWithObject:
[NSNumber numberWithInt:555] forKey:@"MyNumberOne"],
@"MyDictionaryOne",
[NSDictionary dictionaryWithObject:
[NSNumber numberWithInt:777] forKey:@"MyNumberTwo"],
@"MyDictionaryTwo",
nil];
NSLog (@"theMutableDictionary BEFORE = %@", theImmutableDictionary);
NSDictionary* theMutableDictionary = [theImmutableDictionary
mutableCopy];
//Legal
[theMutableDictionary setValue:[NSMutableDictionary dictionary]
forKey:@"MyDictionaryOne"];
//Illegal
//[[theMutableDictionary objectForKey:@"MyDictionaryTwo"]
// setObject:[NSNumber numberWithInt:333] forKey:@"MyNumberTwo"];
//Legal
NSDictionary* theMutableNestedDictionary =
[[theMutableDictionary objectForKey:@"MyDictionaryTwo"]
mutableCopy];
[theMutableNestedDictionary setValue:[NSNumber numberWithInt:333]
forKey:@"MyNumberTwo"];
[theMutableDictionary setValue:theMutableNestedDictionary
forKey:@"MyDictionaryTwo"];
NSLog (@"theMutableDictionary AFTER = %@", theMutableDictionary);
___________________________________________________________
Ricky A. Sharp mailto:[EMAIL PROTECTED]
Instant Interactive(tm) http://www.instantinteractive.com
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