我有多个操作(它们是AFNetworking请求),它们具有需要一些时间才能执行的完成块,并且需要在所有请求的末尾保存一个Core Data对象。

MyCoreDataObject *coreDataObject;

AFHTTPRequestOperation *operation1 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation1 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute1 = responseObject;
    sleep(5);
}];
[operation1 start];

AFHTTPRequestOperation *operation2 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation2 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute2 = responseObject;
    sleep(10);
}];
[operation1 operation2];

[context save:nil];

当然,这不是我想要的,因为请求是异步的。我试过像这样添加NSOperationQueue:
NSOperationQueue *operationQueue = [[NSOperationQueue alloc] init];
[operationQueue setMaxConcurrentOperationCount:2];

AFHTTPRequestOperation *operation1 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation1 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute1 = responseObject;
    sleep(5);
}];
[operationQueue addOperation:operation1];

AFHTTPRequestOperation *operation2 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation2 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute2 = responseObject;
    sleep(10);
}];
[operationQueue addOperation:operation2];

[imageQueue waitUntilAllOperationsAreFinished];
[context save:nil];

看起来好多了。使用waitUntilAllOperationsAreFinished,我的队列将阻塞当前线程,直到我的请求完成为止,但直到成功完成才阻塞,这确实是我所需要的。

关于如何以良好的方式实现这一目标的任何想法?

最佳答案

使用调度组。

dispatch_group_t group = dispatch_group_create();

MyCoreDataObject *coreDataObject;

dispatch_group_enter(group);
AFHTTPRequestOperation *operation1 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation1 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute1 = responseObject;
    sleep(5);
    dispatch_group_leave(group);
}];
[operation1 start];

dispatch_group_enter(group);
AFHTTPRequestOperation *operation2 = [[AFHTTPRequestOperation alloc] initWithRequest:request1];
[operation2 setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    coreDataObject.attribute2 = responseObject;
    sleep(10);
    dispatch_group_leave(group);
}];
[operation2 start];

dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
dispatch_release(group);

[context save:nil];

关于ios - 等待直到所有联网请求都已执行-包括其完成块,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/10643797/

10-11 22:54
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