retain就如2中所述,使用了引用计数,retain引起引用计数加1, release引起引用计数减1,当引用计数为0时,dealloc函数被调用,内存被回收。 Automatic Reference Counting(自动引用计数)简称ARC Strong Reference,强引用。默认类型,不加任何关键字(也可以写成__strong)。相当于之前的retain属性
The weakref attribute marks a declaration as a weak reference. Without arguments, it should be accompanied by an alias attribute naming the target symbol. Optionally, the target may be given as an argument to weakref itself. In either case, weakref implicitly marks the declaration as weak. Witho...
或者用__unsafe_unretained 代替__weak,但是如果用__unsafe_unretained请注意下面的问题。__unsafe_unretained specifies a reference that does not keep the referenced object alive and is not set to nil when there are no strong references to the object. If the object it references is deallocated, the...
The weakref attribute marks a declaration as a weak reference. Without arguments, it should be accompanied by an alias attribute naming the target symbol. Optionally, the target may be given as an argument to weakref itself. In either case, weakref implicitly marks the declaration as weak. Witho...
weak简述 weak表其实是一个hash表,Key是所指对象的地址,Value是weak指针的地址数组,weak是弱引用,所引用对象的计数器不会+1,并在引用对象被释放的时候自动被设置为nil。...weak底层原理 2.1weak 的实现原理可以概括一下三步: 1、初始化时:runtime会调用objc_init...
SideTable是Objective-C中的引用计数表,它持有了weak引用表,也就是weak_table_t类型的weak_table。 struct weak_table_t { weak_entry_t *weak_entries; size_t num_entries; //弱引用项数量 uintptr_t mask; //用于计算哈希的mask uintptr_t max_hash_displacement; //允许的哈希未命中的次数 ...
Aweak reference, simply put,is a reference that isn’t strong enough to force anobject to remain in memory. Weak references allow you to leverage the garbage collector’s ability to determine reachability for you, so you don’t have to do it yourself. You create a weak reference like this...
If all of the references to an object are weak, it can be destroyed. Afterwards, reading the weak references will return nil. Weak references are most commonly used in connection with things such as notifications. You will keep a weak reference to an object and keep sending it messages as ...
当一个对象仅仅被weak reference指向, 而没有任何其他strong reference指向的时候, 如果GC运行, 那么这个对象就会被回收。如果存在强引用同时与之关联,则进行垃圾回收时也不会回收该对象。 WeakReference的语法: WeakReference<T> weakReference = new WeakReference<T>(referent); ...
Weak ReferenceSystem.WeakReference<T>中文(中国) 留言板 GitHub Twitter 微博发布于2015-11-30 由CXuesong 学习CSS布局 http://zh.learnlayout.com/ 分类书签 发表回复 您的邮箱地址不会被公开。 必填项已用 * 标注 评论* 显示名称 * 邮箱* 网站 在此浏览器中保存我的显示名称、邮箱地址和网站...