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Asked: 2026-06-13T23:05:01+00:00

My class has a property: @property (readwrite, atomic) BOOL IsTrue; My understanding of the

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My class has a property:

@property (readwrite, atomic) BOOL IsTrue;

My understanding of the atomic qualifier is that the @synthesized getter/setter for the property will guarantee serialisation of access from different threads, i.e. if producer thread A is setting the property value it will be allowed to complete the set operation before consumer threads B and C are allowed to get the property value (as an aside here, is atomic even necessary for a single byte/POD type?).

Does the volatile keyword provide any further data integrity?

@property (readwrite, atomic) volatile BOOL IsTrue;

What I’m specifically driving at is that is there the possibility of consumer threads getting out-of-date values without the use of volatile?

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  1. Editorial Team

    is there the possibility of consumer threads getting out-of-date
    values without the use of volatile?

    No. From a client’s point of view, the property is just a getter/setter method pair. So any client needs to call objc_msgSend to set or retrieve a value. Function calls are synchronization points in C so there’s no way of getting out of date values (as with direct memory access, where volatile might be helpful).

    The @synthesize’d accessors will take care of serializing access to the underlying value.

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