问题描述
自从我添加了这个 async 请求以来，我收到的xcode错误是将'NSError * const __strong *'发送给类型为'NSError * __ autoreleasing *'的参数，更改保留/释放指针的属性
Ever since I added this async request, I'm getting an xcode error of Sending 'NSError *const __strong *' to parameter of type 'NSError *__autoreleasing *' changes retain/release properties of pointer
...
[NSURLConnection sendAsynchronousRequest:req queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error){
dispatch_async(dispatch_get_main_queue(), ^{
NSDictionary *xmlDictionary = [XMLReader dictionaryForXMLData:data error:&error];
...
});
}];
...
如果我使用 error:nil ，则我的代码可以正常运行，但是对于不使用错误，我感到不安.我该怎么办?
If I use error:nil then my code runs fine, but I feel uneasy about not using errors.. What should I do?
推荐答案
大概是因为您正在重用在完成处理程序中传递给您的 error .它会以 __ strong 的形式传递，然后在需要 __ autoreleasing 的位置传递它.尝试更改为以下代码:
Presumably it's because you're reusing the error passed in to you in the completion handler. It'll be being passed as __strong and then you pass it in where it is required to be __autoreleasing. Try changing to this code:
...
[NSURLConnection sendAsynchronousRequest:req queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error){
dispatch_async(dispatch_get_main_queue(), ^{
NSError *error2 = nil;
NSDictionary *xmlDictionary = [XMLReader dictionaryForXMLData:data error:&error2];
...
});
}];
...
这篇关于ios NSError类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！