How to allow NSMutableDictionary to accept 'nil' values?
objective-c
Solution
There is a non-`nil` object called `NSNull` that is built specifically to represent `nil`s in situations where "plain" `nil` is not acceptable. If you replace your `nil`s with `[NSNull null]` object, `NSDictionary` will take them. You would need to check for `NSNull` on the way out, though.
Note that this is important only when you must differentiate between a value not being set and a value being set to `nil`. If your code is such that it can interpret a missing value as `nil`, you do not need to use `NSNull` at all.
Problem
I have this statement: ``` [custData setObject: [rs stringForColumnIndex:2] forKey: @"email"]; ``` where `[rs stringForColumnIndex:2]` obtained from a SQLite3 d/b has a value of `nil`. The app crashes giving me the error: ``` NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: email)' ``` Is there a way to prevent this? (like a setting for `NSMutableDictionary`?) UPDATE: this is what I finally did: ``` [custData setObject: ([rs stringForColumnIndex:2] != nil? [rs stringForColumnIndex:2]:@"") forKey: @"email"]; ```