13

I'm creating a custom navigation bar class and customizing it's title attributes using the following code:

self.titleTextAttributes = @{ UITextAttributeFont: bariol,
                              UITextAttributeTextColor: [UIColor whiteColor]
                            };

However, when I run the code, it returns the following error message:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderArray initWithObjects:count:]: attempt to insert nil object from objects[1]'

I'm using Xcode 4.6 and running on a device using iOS 6.

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3 Answers 3

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11

It sounds like your bariol object is nil. You can't store nil in a dictionary.

Edit:

Actually, are you sure that's the right line of code? Your error references NSPlaceholderArray, which suggests it's a problem with a @[] literal, not a @{} literal.

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3 Comments

@justin: dictionaryWithObjects:forKeys:count: doesn't use NSArrays. It uses C arrays.
whoops - nonsense returned :) it's still possible that NSArrays are created in the process of constructing the dictionary (or calling another constructor), thus the message of the exception.
@justin: An NSDictionary literal does not construct intermediate NSArrays. So unless -setTitleTextAttributes: is doing something funky, that's not the case.
7

The parameters of the literals (values and keys of your dictionary) must not be nil.

If you prefer a constructor which is less strict, you might consider using +[NSDictionary dictionaryWithObjectsAndKeys:] instead.

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9 Comments

That's not less strict, it just thinks the arguments have stopped if a nil is found where a key was expected. Notably, if you pass a nil object, you'll get the exact same exception.
Most people tend to think that the nil-object-shortcutting behavior is actually bad because it can silently truncate your dictionary.
I switched to dictionaryWithObjectsAndKeys:, works better than @{} for the time being.
Got exactly same problem and fix with dictionaryWithObjectsAndKeys: Thanks.
This is not a good suggestion, more subtle bugs may arise from using that method, like missing data if for example you would populate a response to a server and send as is. The best action is to check data before inserting into a dict.
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5

This error seems to be somewhere else. It's pointing to an array error at object '1'. In your case you have a dictionary and object '1' is UITextAttributeTextColor: [UIColor whiteColor] which will never be nil.

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2 Comments

yes, for those who come looking to confirm the [<number>] on the exception message, it is the 0-indexed array offset of the failing (nil) object. Tested with: NSString *str = nil; NSDictionary *foo = @{NSFontAttributeName:str,NSForegroundColorAttributeName:@"booboo" };
@robm BOOM! Nice one.

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