我应该总是释放自己失败的init方法？ [英] Should I always release self for failed init methods?

问题描述

我应该总是在init里面发生故障时释放自我，或者如果我先初始化了实例变量，我应该怎么做？

Should I always release self when there is a failure inside init, or should I only do so if I have initialized instance variables first?

，这个模式有效吗？有没有时间，我不应该在init方法中释放self，或者我应该假设如果控制流进入init，self至少有一个保留计数1？

To put it another way, is this pattern valid? Is there a time when I shouldn't release self inside an init method, or should I assume that if the control flow enters init, self has at least a retain count of 1?

- (id)init
{
 if ((self = [super init]) == nil)
 {
  [self release];
  return nil;
 }

 //do some init stuff
 if (somethingFailed)
 {
  [self release];
  return nil;
 }
 return self;
}

推荐答案

你的初始化方法失败，那么你应该释放 self 。注意，如果 [super init] 返回 nil ，发送发布到 self as self 是 nil 。这实际上是苹果所皱眉的：

If some check you need in your initialization method fails, then yes you should release self. Note however, that if [super init] returns nil it does not make sense to send release to self as self is nil. This is actually frowned on by Apple:

你应该只调用 [self release] 在故障点。如果从调用超类的初始化器得到 nil ，你不应该调用 release 。

You should only call [self release] at the point of failure. If you get nil back from an invocation of the superclass’s initializer, you should not also call release.

示例：

- (id)init
{
   self = [super init];
   if(self) {
       // do some init stuff

       if (somethingFailed)
       {
          [self release]
          self = nil;
       }
   }

   return self;
}

另请参阅Mac开发中心文档处理初始化失败

Also see the Mac Dev Center documentation on Handling Initialization Failure

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