使用Objective-C和Swift创建内存泄漏

问题描述：

我接受了采访，并被要求用Objective-C和Swift创建内存泄漏。那么如何使用Objective-C和Swift创建内存泄漏？

I had an interview, and I was asked to create a memory leak with Objective-C and Swift.So how to create a memory leak with Objective-C and Swift?

答

您只需要创建一个参考周期。
Obj-C：

You just need to create a reference cycle. Obj-C:

@interface MyClass
@property (strong) MyClass *otherObject;
@end

//...

MyClass *a = [MyClass new];
MyClass *b = [MyClass new];
a.otherObject = b;
b.otherObject = a;

同样适用于Swift：

The same applies to Swift:

class MyClass {
    var otherObject: MyClass?
}

let a = MyClass()
let b = MyClass()
a.otherObject = b
b.otherObject = a

原因： a 成立强烈引用 b ， b 拥有对 a $ c的强引用$ C>。 ARC在运行时没有任何垃圾回收。它只跟踪引用计数。在这种情况下，即使我们在代码中没有引用 a 或 b ，它们的引用计数也将永远不会达到 0 ，因为他们互相引用（除非我们手动打破这个循环）。

Reason: a holds a strong reference to b, and b holds a strong reference to a. ARC doesn't have any garbage collection in runtime. It just tracks the reference count. In this situation, even if we don't have any references to a or b in code, their reference count will never reach 0, since they reference each other (unless we'll break this cycle manually).

UPD （感谢@Sulthan）：你实际上甚至不需要两个对象，强大的自我参考就足够了：

UPD (kudos to @Sulthan): you don't actually even need two objects, a strong self reference is enough:

a.otherObject = a

使用Objective-C和Swift创建内存泄漏

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