Question

Very similar to this question, I am trying to convert a project that uses ASIHTTPRequest & ASIFormDataRequest to ARC.

在我看来,控制员班级中,我经常提到并使用完成区块中的request物体的特性(参考反应代码、回复数据等):

__block  ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:SOME_URL]];    
[request setCompletionBlock:^{   

    if([request responseStatusCode] == 200) ....etc

在改写为非洲排雷中心时,我得到警告:

Capturing request strongly in this block is likely to lead to a retain cycle

如何这样做?

上一个版图中另一个SO用户指出,只要添加__weak<>/code>,就可以在完成栏目之前提出释放请求,我认为这是真实的。



我怎么能够把这些财产适当参照到ARC/ARC之下的完工/休假区?

Answer 1


(我宣读你对另一个问题的评论)

在使用<代码>ASIHTTPRequest实施另外几个模块之后,我得知,最好在提及你的请求时保留<代码>strong<>。您可以:

self.request = [ASIFormDataRequest requestWithURL:[NSURL URLWithString:SOME_URL]];
__weak ASIFormDataRequest *weakRequest = self.request; // __block directive not needed since we only access the instance s properties. 
[self.request setCompletionBlock:^{   

    if([weakRequest responseStatusCode] == 200)
    // ...

这样,你仍然能够控制<代码>。甚至在你开始申请之后(例如取消申请)。您可在以下网址上填写: Self.request = nil;, 当您重新准备发布请求时,可在您的填写栏或内填写。母体反对清理方法。



<>Update:

如果你重新瞄准第5号行动前,则共同点:使用<代码>unsafe_unretained而不是_we。之所以如此,是因为考虑到<代码>ASIHTTPRequest.m,各栏号为nil,载于其dealloc((即:应否执行)。虽然我已经进行过检测,但这样,我们就能够保证仍然能够与乌克兰航天局进行测试。

Note:

The only safe way to cancel an ASIHTTPRequest object is to call its clearDelegatesAndCancel method. I ve been bitten by some nasty bugs when I was just using the plain cancel one.

Answer 2

If you re targeting iOS versions before 5.0, that do not include weak support:

__unsafe_unretained __block ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];

Answer 3

I ve found this answer to be helpful: https://stackoverflow.com/a/7735770/133875

It says to use __unsafe_unretained as well as __block

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