Question

我在行上获得了一个EXC_BAD_ACCESS / KERN_INVALID_ADDRESS“self handleError：error ..etc”

我认为该块会保留自己？ “self”是一个viewController，可能会从堆栈中弹出，但是不应该保留它？

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

Answer 1

如果self被解除分配确实是你真正的问题，那么完整的解决方案是在块内强烈引用self的弱引用，这样你就可以摆脱在块内执行时释放它的风险：

强烈引用块内的弱指针。

__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); 
};

避免直接使用变量，因为它会导致保留周期。如果直接在块中使用实例变量，则块将捕获self，因此您必须使用其访问器引用实例变量。

__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
};

如果你直接使用实例变量：

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

编译器将_objectID解释为self->_objectID，其中self被块捕获。

Answer 2

你应该避免在可能的情况下使用自己。

试试这个：

__weak __typeof(self)weakSelf = self;

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

在块中自我EXC_BAD_ACCESS

2 个答案: