Objective-C：块是在强方法还是弱方法中定义的？

Question

I have a situation like this:

- (void)someMethod
{
    __weak typeof(self) weakSelf = self;

    void (^myBlock1)(void) = ^{
        // ... do stuff
    };

    void (^myBlock2)(void) = ^{
        [weakSelf doSomeHeavyNetworkCall2:^{
            myBlock1();
        }];
    };

    [self doSomeHeavyNetworkCall1:^{
        myBlock2();
    }];
}

What is the life cycle of myBlock1 and myBlock2 in this case? Should I be checking for nil like this?

void (^myBlock2)(void) = ^{
    [weakSelf doSomeHeavyNetworkCall2:^{
        if (myBlock1) {
            myBlock1();
        }
    }];
};

[self doSomeHeavyNetworkCall1:^{
    if (myBlock2) {
        myBlock2();
    }
}];

Also if I wrap the entire someMethod in @synchronized , am I guaranteed to have the blocks around?

Answer 1

Local variables are strong by default in Objective-C so myBlock1 and myBlock2 are strong. There is no need for the if (myBlock1) and if (myBlock2) checks.

Wrapping the contents of someMethod with @synchronized has no effect on the lifecycle of these variables.