NSMutableDictionary setObject:forKey did't work when value is NSMutableArray

dict is NSMutableDictionary; array is NSMutableArray and is NOT nil;

The code:

[dict setObject:array forKey:@"key"];

There is no e开发者_如何学Crror or warning but the dict is null,nothing is set or added.

When I use the code below,it works:

[dict setObject:[NSArray arrayWithArray:array] forKey:@"Key"];

Can anyone tell me why ?

Update: Both dict and array are local variables and have been initialized.The dict is nil.

NSLog(@"%@", array) has printed the value of array:

({"Title":"firstTitle","Date":"20110101"},{"Title":"secondTitle","Date":"20110102"})

UPDATE:

I have made a mistake.The array is not null at first,but I emptied it in follow operation.

Thanks for @Bavarious.

You're aware that you're using different capitalizations of "key", right? @"Key" is not the same thing as @"key".

I think you have not initialized array in 1st statement. check if its allocated memory or not?

The code seems to be correct. Most probably your array is nil. When using arrayWithArray, the inserted object will be an array, even if its value itself is set to nil.