ios - Do I need to check for nil on my strongSelf = weakSelf assignment inside a block? -

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for example, i'm using svinfinitescrolling (https://github.com/alexanderedge/svinfinitescrolling).

i have code looks this...

- (void)initializeinfinitescrollingfortableview {     __weak myviewcontroller *weakself = self;      [self.tableview addinfinitescrollingwithactionhandler:^{         myviewcontroller *strongself = weakself;         if (!strongself.endreached) {             [strongself fetchdata];         }         else {             [strongself.tableview.infinitescrollingview stopanimating];         }     }]; }

what i'm wondering is... need check strongself nil before using this...

... [self.tableview addinfinitescrollingwithactionhandler:^{     myviewcontroller *strongself = weakself;     if (strongself) { // <== ** needed? **         if (!strongself.endreached) {

here why ask. point #3 on link (http://www.apeth.com/iosbook/ch12.html#exstrongweakdance) says "the nil test because, in multithreaded situation, our weak reference self may have vanished out under before previous step; nil, because it’s arc weak reference, , in case there no point continuing."

is check needed? thought first time used reference weakself within block, retained duration of expression?

i think in line:

if (!strongself.endreached) {

this evaluate yes if self nil, not not intend.

it happens code correct thing (do nothing) because both clauses use self call methods , nothing happen. end result same if had nil-check execution path wrong. might have consequences in future if adds code doesn't use self.


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