objective-c - 关联对象会自动释放吗？

Question

注意:这个其他问题似乎相关但不是:When does an associated object get released?

我正在向 UIView 实例添加第二个描述，如下所示:

- (void) setSecondDescription:(UIView*)view description2:(NSString*)description2 {
    objc_setAssociatedObject (view,&key,description2,OBJC_ASSOCIATION_RETAIN);
}

- (NSString*) secondDescription:(UIView*)view {
    return (id)objc_getAssociatedObject(view, &key);   
}

如果 UIView 释放，关联的描述 2 会被释放吗？有什么方法可以让它自动发生吗？

Answer 1

如果您想真正查看整个 dealloc 时间线的描述，请查看 WWDC 2011，Session 322，36:22。然而，这是基本的概要(我想记住它，所以这是我的一段代码中的实际注释)。

请注意，关联对象在生命周期结束时被释放。

// General Information
// We take advantage of the documented Deallocation Timeline (WWDC 2011, Session 322, 36:22).
// 1. -release to zero
//     * Object is now deallocating and will die.
//     * New __weak references are not allowed, and will get nil.
//     * [self dealloc] is called
// 2. Subclass -dealloc
//     * bottom-most subclass -dealloc is called
//     * Non-ARC code manually releases iVars
//     * Walk the super-class chain calling -dealloc
// 3. NSObject -dealloc
//     * Simply calls the ObjC runtime object_dispose()
// 4. object_dispose()
//     * Call destructors for C++ iVars
//     * Call -release for ARC iVars
//     * Erase associated references
//     * Erase __weak references
//     * Call free()