ios - 在 ARC 下，IBOutlets 应该强还是弱？

Question

我正在使用 ARC 专门为 iOS 5 开发。 IBOutlets 到 UIViews(和子类)应该是 strong 还是 weak？

以下内容:

@property (nonatomic, weak) IBOutlet UIButton *button;

将摆脱所有这些:

- (void)viewDidUnload
{
    // ...
    self.button = nil;
    // ...
}

这样做有什么问题吗？模板使用 strong 以及从“Interface Builder”编辑器直接连接到标题时创建的自动生成的属性，但为什么呢？ UIViewController 已经有一个对其 view 的 strong 引用，该引用保留了它的 subview 。

Answer 1

警告，过时的答案:根据 WWDC 2015，此答案不是最新的，正确答案请参阅 accepted answer (丹尼尔霍尔)以上。此答案将留作记录。

---

总结自 developer library :

From a practical perspective, in iOS and OS X outlets should be defined as declared properties. Outlets should generally be weak, except for those from File’s Owner to top-level objects in a nib file (or, in iOS, a storyboard scene) which should be strong. Outlets that you create will therefore typically be weak by default, because:

• Outlets that you create to, for example, subviews of a view controller’s view or a window controller’s window, are arbitrary references between objects that do not imply ownership.

• The strong outlets are frequently specified by framework classes (for example, UIViewController’s view outlet, or NSWindowController’s window outlet).

  @property (weak) IBOutlet MyView *viewContainerSubview;
  @property (strong) IBOutlet MyOtherClass *topLevelObject;