CFBinaryHeap

RacTestScheduler

用CFBinaryHeapRef存储RACTestSchedulerAction

RACTestSchedulerAction是对 date， block， disposable的封装。

使用CFBinaryHeapAddValue方法把action写入。
使用CFBinaryHeapGetMinimumIfPresent 方法把action取出。

    CFBinaryHeapCallBacks callbacks = (CFBinaryHeapCallBacks){
        .version = 0,
        .retain = &RACRetainScheduledAction,
        .release = &RACReleaseScheduledAction,
        .copyDescription = &CFCopyDescription,
        .compare = &RACCompareScheduledActions
    };

    _scheduledActions = CFBinaryHeapCreate(NULL, 0, &callbacks, NULL);


static CFComparisonResult RACCompareScheduledActions(const void *ptr1, const void *ptr2, void *info) {
    RACTestSchedulerAction *action1 = (__bridge id)ptr1;
    RACTestSchedulerAction *action2 = (__bridge id)ptr2;
    return CFDateCompare((__bridge CFDateRef)action1.date, (__bridge CFDateRef)action2.date, NULL);
}

是按照date的顺序出队列的。

也许取出有序性，是使用该结构的原因～～

1、问题1
不改变对象所有权。actionPtr拿到之后，并没有保持强引用，然后立即调用CFBinaryHeapRemoveMinimumValue将actionPtr从CFBinaryHeapRef中删除，这样后面actionPtr不就是野指针了吗？

            const void *actionPtr = NULL;
            if (!CFBinaryHeapGetMinimumIfPresent(self.scheduledActions, &actionPtr)) break;

            //不改变对象所有权。actionPtr拿到之后，并没有保持强引用，然后立即调用CFBinaryHeapRemoveMinimumValue将actionPtr从CFBinaryHeapRef中删除，这样后面actionPtr不就是野指针了吗？
            RACTestSchedulerAction *action = (__bridge id)actionPtr;
            CFBinaryHeapRemoveMinimumValue(self.scheduledActions);

            if (action.disposable.disposed) continue;

2、c类型 用assign
assign不改变对象引用计数

///assign不改变对象引用计数
@property (nonatomic, assign, readonly) CFBinaryHeapRef scheduledActions;

dealloc中需要释放