iphone - NSOperationQueue 和 ASIHTTPRequest

Question

我正在为围绕 ASIHTTPRequest 编写的包装类编写测试用例。由于我无法确定的原因，我的测试用例在 ASIHTTPRequest 完成之前就失败了。

以下是程序流程的工作原理。

1. 从我的测试用例开始。
2. 初始化我的 http 引擎对象，指示它创建一个新列表
3. 创建新的 ASIHTTPRequest 对象并进行设置。
4. 将请求添加到操作队列。
5. 等到队列为空
6. 检查我的委托(delegate)方法是否被调用，如果没有，则测试失败。

现在，大多数情况下一切正常并且测试通过，但有时会失败，因为在操作队列将控制权返回给我的等待方法之后调用了我的委托(delegate)方法。

测试用例

// Set my flags to 'NO'
- (void)setUp {
    requestDidFinish = NO;
    requestDidFail = NO;
}

- (void)testCreateList {
    NSString *testList = @"{\"title\": \"This is a list\"}";

    JKEngine *engine = [[JKEngine alloc] initWithDelegate:self];
    NSString *requestIdentifier = [engine createList:jsonString];

    [self waitUntilEngineDone:engine];
    NSString *responseString = responseString_;
    [engine release];

    GHAssertNotNil(requestIdentifier, nil);
    GHAssertTrue(requestDidFinish, nil);
    GHAssertTrue([responseString hasPrefix:@"{\"CreateOrEditListResult\""], nil);

}

// Puts the test into a holding pattern until the http request is done
- (void)waitUntilEngineDone:(JKEngine *)engine {
    [engine waitUntilFinishedRunning]; 
}

// The delegate method called on successful completion
- (void)requestFinished:(NSString *)requestIdentifier withResponse:(NSString *)response {
    NSLog(@"request did finish");
    requestDidFinish = YES;
    responseIdentifier_ = [requestIdentifier retain];
    responseString_ = [response retain];
}

引擎代码

- (NSString *)createList:(NSString *)list {
    ASIHTTPRequest *request = [[ASIHTTPRequest alloc] initWithURL:[NSURL URLWithString:url]];
    [request addRequestHeader:@"Content-Type" value:kContentType];
    [request setRequestMethod:kPOST];
    request.delegate = self;

    [request appendPostData:[list dataUsingEncoding:NSUTF8StringEncoding]];

    NSString *requestIdentifier = [NSString stringWithNewUUID];

    [operationQueue_ addOperation:request];
    [operationDictionary_ setObject:request forKey:requestIdentifier];

    return requestIdentifier;
}

// This is the ASIHTTPRequest delegate method that's called on success
//   but it sometimes isn't called until AFTER the operationQueue finishes running
- (void)requestFinished:(ASIHTTPRequest *)request {
    DLog([request responseString]);

    BOOL canNotifiyDelegate = [self.delegate respondsToSelector:@selector(requestFinished:withResponse:)];
    if (canNotifiyDelegate) {
        NSArray *keyArray = [operationDictionary_ allKeysForObject:request];
        NSString *requestIdentifier = [keyArray objectAtIndex:0];
        [operationDictionary_ removeObjectForKey:requestIdentifier];

        if ([keyArray count] != 1) {
            ALog(@"It looks like a request was added to the operation dictionary multiple times. There's a bug somewhere.", nil);
        }

        [self.delegate requestFinished:requestIdentifier withResponse:[request responseString]];
    }
}

- (void)waitUntilFinishedRunning {
    [operationQueue_ waitUntilAllOperationsAreFinished];
}

Answer 1

这就是 ASIHTTPRequest 的工作方式。委托(delegate)方法在主线程上调用，并且对委托(delegate)的调用不会阻塞请求线程，因此完全有可能在队列完成后调用您的委托(delegate)。