ios - Why nonatomic is still used even though it might cause data error? -

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this question has answer here:

i've read through several explanation on differences between atomic , nonatomic. in this link, says:

with "atomic", synthesized setter/getter ensure whole value returned getter or set setter, regardless of setter activity on other thread. is, if thread in middle of getter while thread b calls setter, actual viable value -- autoreleased object, -- returned caller in a.

in nonatomic, no such guarantees made. thus, nonatomic considerably faster "atomic".

nonatomic qualifier may cause access error when using setter , getter @ same time. what's point of using it, although it's faster atomic?

performance. if declare properties atomic, accessors use locks ensure values retrieved , set. if don't need - sure 1 thread have access variable , you're incurring performance penalty locks without getting benefit. it's decide need lock on object or not.


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