1. bugly 崩潰日志如下

image.png

2. 定位到相應(yīng)的代碼段

- (void)dealloc {
    self.splash.delegate = self;
    self.splash = nil;
}

• Xcode 報(bào)錯(cuò)日志如下

 if (deallocating) {
        _objc_fatal("Cannot form weak reference to instance (%p) of "
                    "class %s. It is possible that this object was "
                    "over-released, or is in the process of deallocation.",
                    (void*)referent, object_getClassName((id)referent));
    }

3. 崩潰原因

• 因?yàn)槭终`，將 self.splash.delegate = nil; 寫(xiě)成了 self.splash.delegate = self;
• 在 dealloc 的時(shí)候，self 會(huì)被標(biāo)記成 deallocating 狀態(tài)，這時(shí)候進(jìn)行 weak 賦值，就會(huì)崩潰。
• 在weak_register_no_lock方法中
• runtime 檢查引用計(jì)數(shù)的個(gè)數(shù)來(lái)判斷對(duì)象是否在 deallocting
• 如果是在deallocting就會(huì)報(bào)錯(cuò)

4. weak_register_no_lock代碼

id 
weak_register_no_lock(weak_table_t *weak_table, id referent_id, id *referrer_id)
{
    objc_object *referent = (objc_object *)referent_id;
    objc_object **referrer = (objc_object **)referrer_id;

    if (!referent  ||  referent->isTaggedPointer()) return referent_id;

    // ensure that the referenced object is viable
    bool deallocating;
    if (!referent->ISA()->hasCustomRR()) {
        deallocating = referent->rootIsDeallocating();
    }
    else {
        BOOL (*allowsWeakReference)(objc_object *, SEL) = 
            (BOOL(*)(objc_object *, SEL))
            object_getMethodImplementation((id)referent, 
                                           SEL_allowsWeakReference);
        if ((IMP)allowsWeakReference == _objc_msgForward) {
            return nil;
        }
        deallocating =
            ! (*allowsWeakReference)(referent, SEL_allowsWeakReference);
    }

    if (deallocating) {
        _objc_fatal("Cannot form weak reference to instance (%p) of "
                    "class %s. It is possible that this object was "
                    "over-released, or is in the process of deallocation.",
                    (void*)referent, object_getClassName((id)referent));
    }

    // now remember it and where it is being stored
    weak_entry_t *entry;
    if ((entry = weak_entry_for_referent(weak_table, referent))) {
        append_referrer(entry, referrer);
    } 
    else {
        weak_entry_t new_entry;
        new_entry.referent = referent;
        new_entry.out_of_line = 0;
        new_entry.inline_referrers[0] = referrer;
        for (size_t i = 1; i < WEAK_INLINE_COUNT; i++) {
            new_entry.inline_referrers[i] = nil;
        }

        weak_grow_maybe(weak_table);
        weak_entry_insert(weak_table, &new_entry);
    }

    // Do not set *referrer. objc_storeWeak() requires that the 
    // value not change.

    return referent_id;
}