Re: odd problem with NSMutableDictionary and initWithContentsOfFile

FROM : Jason Coco
DATE : Thu May 29 17:44:56 2008

On May 29, 2008, at 10:47 , Jens Alfke wrote:

>
> On 29 May '08, at 6:41 AM, Leslie Smith wrote:
>

>> I found out what I was doing wrong:  rather than
>>
>> [SimParamnames initWithContentsOfFile: aFile];
>>
>> I should have had
>>
>> SimParamnames = [SimParamnames initWithContentsOfFile: aFile];

>
> No. As two people have said already, *you can't initialize an object 
> more than once*. The only time an init method is to be called is 
> right after -alloc, when the object is first created. Calling it 
> again will unexpectedly reset part of the object's state, and 
> probably mess it up.
>
> What you should do instead of the above line is
>     [SimParamnames release];    // to get rid of the old object
>     SimParamnames = [[NSDictionary alloc] initWithContentsOfFile: 
> aFile];  // new object


If for some reason you absolutely want/need to use the 
NSMutableDictionary that you originally allocated, you can do 
something like this:

[SimParamnames removeAllObjects];
[SimParamnames addEntriesFromDictionary:[NSDictionary 
dictionaryWithContentsOfFile:aFile]];

That should work as expected without releasing the original mutable 
dictionary (assuming you really do need it for something you cut in 
the example).