自我阻止中的EXC_BAD_ACCESS

Question

我在“ self handleError：error ..etc”行上得到一個EXC_BAD_ACCESS / KERN_INVALID_ADDRESS

我以為塊會保留自我？ “ self”是一個可能從堆棧中彈出的viewController，但是不應該保留它嗎？

[[PWGamesResource sharedInstance] createRandomGameRequest:requestDict
        withFailure:^(NSError *error) {
            [self handleError:error withTryAgain:^{
                [self sendNewRandomGameRequest:difficulty];
            }];
        }];

Answer 1

如果將self釋放確實是您的真正問題，那么完整的解決方案是在塊內強烈引用self的弱引用，這樣您就可以避免在塊內執行時將其釋放的風險：

強烈引用塊內的弱指針。

__weak MyObject *weakSelf = self; // a weak reference of self so you can avoid any retain cycles
myBlock = ^{
  MyObject *innerSelf = weakSelf; // a block-local strong reference so that you can avoid to have weakSelf deallocated while executing
  NSLog(@"MyObject: %@", innerSelf); 
};

避免直接使用變量，因為這會導致保留周期。 如果直接在塊內使用實例變量，則該塊將捕獲self，因此您必須使用其訪問器來引用實例變量。

__weak MyObject *weakSelf = self;
myBlock = ^{
    MyObject *innerSelf = weakSelf; // a block-local strong reference
    NSLog(@"MyObject: %@", innerSelf);
    NSLog(@"MyObject ID: %d", innerSelf.objectID);// accessing the property through the block's strong reference to self
};

如果您像這樣直接使用實例變量：

NSLog(@"MyObject ID: %d", _objectID);

編譯器將_objectID解釋為self->_objectID ，其中self被您的塊捕獲。

Answer 2

您應盡可能避免在塊中使用self。

嘗試這個：

__weak __typeof(self)weakSelf = self;

[[PWGamesResource sharedInstance] createRandomGameRequest:requestDict
        withFailure:^(NSError *error) {
            [weakSelf handleError:error withTryAgain:^{
                [weakSelf sendNewRandomGameRequest:difficulty];
            }];
        }];