为什么我的NSOperation子类从未完成？ [英] Why is my NSOperation subclass never finishing?

问题描述

我有一个 NSOperation 子类，我想同时运行。

I have an NSOperation subclass that I want to run concurrently.

我的理解是，工作：

• 我需要定义 isConcurrent 才能返回 c> li>我需要发送 isExecuting 和 isFinished 的KVO通知。


• isExecuting 和 @synthesize 会自动传送适当的KVO通知> isFinished 已更改。

• I need to define isConcurrent to return YES.
• I need to define the start method
• I need to send KVOs notification for isExecuting and isFinished when it's done.
• Using @synthesize will automatically send the appropriate KVO notifications when the values for isExecuting and isFinished are changed.

尽管如此，我已验证我的队列不会移动到下一个

Despite this, I have verified that my queue never moves on to the next item.

这里是我的代码的肉：

@interface MyOperation()

@property (readwrite) BOOL isExecuting;
@property (readwrite) BOOL isFinished;

@end

@implementation MyOperation

- (void)start
{
    @autoreleasepool {
        self.isExecuting = YES;
        self.HTTPOperation = [[AFHTTPRequestOperation alloc] initWithRequest: URLRequest];

        _HTTPOperation.completionBlock = [^{
            [self completed];

            self.isExecuting = NO;
            self.isFinished = YES;
        } copy];

        [_HTTPOperation start];
    }
}

- (BOOL)isConcurrent
{
    return YES;
}

- (void)completed
{
}

@end

我缺少什么？

（这是在iPhone上， ）

(This is on an iPhone, but I can't imagine that matters.)

推荐答案

它看起来像什么KVO通知 @synthesize 发送不足以 NSOperationQueue 继续。

It looks like whatever KVO notifications @synthesize sends aren't enough for NSOperationQueue to move on.

手动发送通知修复问题：

Sending the notifications manually fixes the problem:

- (void)start
{
    @autoreleasepool {
        [self willChangeValueForKey:@"isExecuting"];
        self.isExecuting = YES;
        [self didChangeValueForKey:@"isExecuting"];

        NSURLRequest *URLRequest = [self buildRequest];
        if (!URLRequest) {
            [self willChangeValueForKey:@"isFinished"];
            [self willChangeValueForKey:@"isExecuting"];
            _isExecuting = NO;
            _isFinished = YES;
            [self didChangeValueForKey:@"isExecuting"];
            [self didChangeValueForKey:@"isFinished"];
            return;
        }

        self.HTTPOperation = [[AFHTTPRequestOperation alloc] initWithRequest: URLRequest];

        _HTTPOperation.completionBlock = [^{
            [self completed];

            [self willChangeValueForKey:@"isFinished"];
            [self willChangeValueForKey:@"isExecuting"];
            _isExecuting = NO;
            _isFinished = YES;
            [self didChangeValueForKey:@"isExecuting"];
            [self didChangeValueForKey:@"isFinished"];
        } copy];

        [_HTTPOperation start];
    }
}

另请参阅：

• 为什么NSOperation禁用自动键值观察？

• Why does NSOperation disable automatic key-value observing?

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