Swift Automatic Reference Counting

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accordingly, strong reference object cannot of type optional, object kept in heap until reference deallocated. weak reference of type optional, object can deallocated , reference set nil. unowned references fall in-between; neither strong nor of type optional. instead, compiler assumes object unowned reference points not deallocated long reference remains allocated. typically used in situations target object holds reference object holds unowned reference.



swift differs objective-c in usage , encouragement of value types instead of reference types. types in swift standard library value types , copied reference, whereas classes , closures reference types , passed reference. because value types copied when passed around, deallocated automatically reference created them.








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