NSOperation与补全块 [英] NSOperation with completition block

问题描述

我有一些图像处理需要很多时间和资源，因此我使用

I have some image processing that take much time and resources, so i use NSOperation + NSOperatioQueue + delegate for callBack. and all work.

现在我要使用块，因为例如在tableView中使用它非常优雅和简单.

now i want to use blocks because its much elegant and simple to use in a tableView for example.

我需要做的就像 AFJSONRequestOperation 一样:

what i need to do is just like AFJSONRequestOperation for example:

NSURL *url = [NSURL URLWithString:@"url"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
NSLog(@"App.net Global Stream: %@", JSON);
 } failure:nil];
[operation start];

在此示例中，我看不到任何operationQueue！我该怎么办?

in this example i don't see any operationQueue ! how can i do the same?

    [ImageManagerOperation modifyImage:(UIImage*)image completitionBlock:(void (^)(UIImage *modifiedImage))complete];

其中ImageManagerOperation是NSOperation.

where ImageManagerOperation is an NSOperation.

我知道我可以设置一个完成块，但是我仍然需要在队列中添加操作.

I know that i can set a Completion Block, but i still need to add the operation in a queue.

我想最小化代码中的行号(如果可能的话:)).

i want to minimize the line number in my code (if possible :) ).

推荐答案

通常，NSOperation中的代码是同步的. NSOperationQueue提供在后台运行代码所需的线程.因此，您将操作添加到队列中，然后队列在后台线程上的操作上调用start.

Normally the code in an NSOperation is synchronous. The NSOperationQueue provides the threads needed to run the code in the background. So you add your operation to a queue and the queue then calls start on your operation on a background thread.

AFJSONRequestOperation是称为concurrent的NSOperation的特殊类型，这意味着该操作已经在内部提供了自己的后台线程.在某些情况下，您可以在队列外部调用concurrent操作的start方法.因为该操作已经提供了它自己的后台线程，所以它仍将在后台运行.在这种情况下，可以直接调用start只是为了最小化示例中显示的代码.

AFJSONRequestOperation is a special type of NSOperation called concurrent, this means the operation already provides it's own background threads internally. In some circumstances you may call the start method of a concurrent operation outside of a queue. Because the operation already provides it's own background threads it would still run in the background. In this case start might be called directly just to minimise the code shown in the example.

通常，您仍然会向NSOperationQueue添加concurrent操作，因为您想利用队列提供的其他功能，例如管理dependancies和maxConcurrentOperationCount.

Normally you would still add concurrent operations to an NSOperationQueue because you want to take advantage of the other things the queue provides such as managing dependancies and the maxConcurrentOperationCount.

因此，只需为自己创建一个NSOperationQueue并将其添加操作即可.您无需呼叫start队列将为您完成此操作.

So just create yourself an NSOperationQueue and add your operation to it. You wont need to call start the queue will do this for you.

这篇关于NSOperation与补全块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IT屋！