NSProgress::completedUnitCount 设置器挂起答案

【问题标题】：NSProgress::completedUnitCount setter hangsNSProgress::completedUnitCount 设置器挂起
【发布时间】：2016-01-04 11:27:41
【问题描述】：

(void)URLSession:(NSURLSession *)session 任务：（NSURLSessionTask *）任务 didSendBodyData:(int64_t)bytesSent totalBytesSent:(int64_t)totalBytesSent totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend { self.progress.completedUnitCount = totalBytesSent; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 这挂在 ios 9.0 有什么想法该怎么办？？？
(void)URLSession:(NSURLSession *)会话任务:(NSURLSessionTask *)任务 didSendBodyData:(int64_t)bytesSent totalBytesSent:(int64_t)totalBytesSent totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend;在主线程上调用并不重要

(lldb) bt * 线程#1：tid = 0xd6e1, 0x00000001984a0c6c libsystem_kernel.dylibsemaphore_wait_trap + 8, queue = 'com.apple.main-thread', activity = 'send control actions', 1 messages, stop reason = signal SIGSTOP * frame #0: 0x00000001984a0c6c libsystem_kernel.dylibsemaphore_wait_trap + 8 帧#1：0x000000019857a97c libsystem_platform.dylib_os_semaphore_wait + 24 frame #2: 0x00000001007bd428 libdispatch.dylib_dispatch_barrier_sync_f_slow + 600 帧#3：0x00000001835af270 Foundation-[NSConcreteObservationBuffer _receiveBox:] + 248 frame #4: 0x00000001836180b0 Foundation_NSKVO1AdaptorDeliver + 388 帧#5：0x0000000183617ea0 Foundation_NSKVO1AdaptorSlowDeliver + 264 frame #6: 0x0000000183523b84 Foundation-[NSKeyValueObservance observeValueForKeyPath:ofObject:change:context:] + 424 帧#7：0x00000001834ffdd4 FoundationNSKeyValueNotifyObserver + 304 frame #8: 0x00000001834ff8fc FoundationNSKeyValueDidChange + 404 帧#9：0x00000001834ea114 Foundation-[NSObject(NSKeyValueObserverNotification) didChangeValueForKey:] + 120 frame #10: 0x000000018258fab0 CoreFoundation__53-[__NSArrayM enumerateObjectsWithOptions:usingBlock:]_block_invoke + 132 帧 #11: 0x000000018258f9a8 CoreFoundation-[__NSArrayM enumerateObjectsWithOptions:usingBlock:] + 308 frame #12: 0x00000001836cc158 Foundation-[NSProgress _setValueForKeys:settingBlock:] + 600 第 13 帧：0x00000001836cc87c Foundation`-[NSProgress setCompletedUnitCount:] + 124

PS：如果我避免将 UIProgressView::observedProgress 设置为 NSProgress，它可以正常工作！？

【问题讨论】：

标签： ios uikit nsprogress

【解决方案1】：

忙等待解决

-(void)showUploadingUI
{
myHardAssert([[NSThread currentThread] isMainThread], @"");
self.progressView.hidden = NO;
NSProgress *progress = urlsession.progress;
if( [self.progressView respondsToSelector:@selector(observedProgress)]) {
// this causes hang     self.progressView.observedProgress = progress;
}
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
    while(progress.completedUnitCount < progress.totalUnitCount) {
        dispatch_sync(dispatch_get_main_queue(), ^{
            self.progressView.progress = progress.fractionCompleted;
        });
        [NSThread sleepForTimeInterval:0.033];
    }
    dispatch_sync(dispatch_get_main_queue(), ^{
        self.progressView.progress = 1;
    });

....

附带的好处是向后兼容 ios

【讨论】：

【解决方案2】：

男孩这样做对我有帮助。递增 Progress.completedUnitCount 时，我的应用程序冻结了。（在主线程上。）我假设这会触发一个设置器，因为有一个副作用——移动进度条，这是这样做的全部原因。

我的 Swift 4 解决方案是这样包装调用：

DispatchQueue.global(qos: .utility).async {
    self._decompressionProgress.completedUnitCount += 1
}

我仍然不太明白为什么会这样......很多事情都不同。

【讨论】：