Why would an instance of NSMutableArray be immutable?

James Walker

I was trying to add an object to an array and got an exception saying that I was trying to modify an immutable object. I set a breakpoint just before the addObject: line, and said to lldb

po [formatsOfSize isKindOfClass: [NSMutableArray class]]

and the reply was '\x01'. So it should be mutable, no? Is there a better run-time test for mutability?

If it's a clue,

po [formatsOfSize class]



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