Question

I get some data from the server and save it to NSDictionary then I want to initialise NSMutableDictionary with that NSDictionary.

NSDictionary  * const received = [self serverData];
NSMutableDictionary * const results = [NSMutableDictionary dictionaryWithDictionary:received];

And If I get empty JSON from the server and consequently my NSDictionary will be empty how can I use dictionaryWithDictionary for an empty one? I use this

NSDictionary * const received = [self serverData];
NSMutableDictionary * const results;
if (![received count]) {
    results = [NSMutableDictionary dictionary];
}
else
{
    results = [NSMutableDictionary dictionaryWithDictionary:received];
}

But it seems a code smell. May be there are more elegant solutions?

Answer 1

I would make a category on NSDictionary that provides for such a safe setting.

+ (NSMutableDictionary *)safeDictionaryWithDictionary:(NSDictionary *)dictionary
{
    return [NSMutableDictionary dictionaryWithDictionary:(dictionary ? dictionary : @{});
}