如何更新NSProgressIndicator？

Question

我对NSProgress有意见。问题是，NSProgressIndicator没有在过程中进行更新，并且在流程结束时只显示一小部分已完成的部分。localizedDescription也只显示在过程的结束，但作为100%完成。

因此，我有一个类，其中有一个使用findRepeatsWithProgressReporting的NSProgress方法。

class TestProgress: NSObject, ProgressReporting
{
    let progress: Progress

    override init()
    {
        progress = Progress()
        super.init()
    }

    func findRepeatsWithProgressReporting(stringToSearch: String, minimalLength: Int, maximalLength: Int) -> [String]
    {
        var arrayOfRepeats = [String]()

        progress.totalUnitCount = Int64((minimalLength...maximalLength).count)

        for i in minimalLength...maximalLength
        {
            let arrayOfStrings = stringToSearch.chopString(stringOut: stringToSearch, length: i)
            let arrayOfUniqueStrings = Array(Set(arrayOfStrings))

            for each in arrayOfUniqueStrings
            {
                let arrayOfNSRanges = stringToSearch.searchForNSRangesOfStringInString(stringOut: stringToSearch, stringIn: each)

                var positions = String()

                if arrayOfNSRanges.count > 1
                {
                    for each1 in arrayOfNSRanges
                    {
                        let repeatStart = String(each1.location + 1)
                        let repeatEnd = String(each1.location + each1.length)
                        positions += "(" + repeatStart + "-" +  repeatEnd + ")"
                    }
                    let stringToShow = each + " " + positions
                    arrayOfRepeats.append(stringToShow)
                }
            }
            progress.completedUnitCount += 1
        }
        return  arrayOfRepeats
    }

}

然后，在myVewContrloler中，我让parentProgress repeatsProgress具有totalUnitCount: 10，并将方法findRepeatsWithProgressReporting作为childProgress的任务添加到使用repeatsProgress.becomeCurrent(withPendingUnitCount: 10)的parentProgress repeatsProgress中。

private var progressObservationContext = 0

class myVewContrloler: NSViewController
{
    ...

    var testProgress = TestProgress ()
    var repeatsProgress = Progress() 

    @IBOutlet weak var repeatsSearchProgressBar: NSProgressIndicator!
    @IBOutlet weak var repeatsPercentText: NSTextField!

    @IBOutlet weak var minimalLength: NSTextField!
    @IBOutlet weak var maximalLength: NSTextField!
    @IBOutlet var foundRepeats: NSTextView!

    @IBAction func actionFindRepeats(_ sender: AnyObject)
    {
        repeatsProgress = Progress(totalUnitCount: 10)

        let options : NSKeyValueObservingOptions = [.new, .old, .initial, .prior]
        repeatsProgress.addObserver(self, forKeyPath: "fractionCompleted", options: options, context: &progressObservationContext)
        repeatsProgress.addObserver(self, forKeyPath: "localizedDescription", options: options, context: &progressObservationContext)

        var arrayOfRepeats = [String]()

        repeatsProgress.becomeCurrent(withPendingUnitCount: 10)
        arrayOfRepeats = testProgress.findRepeatsWithProgressReporting(stringToSearch: stringToSearch, minimalLength: minimalLength.integerValue, maximalLength: maximalLength.integerValue)

        ...

        repeatsProgress.removeObserver(self, forKeyPath: "fractionCompleted")
        repeatsProgress.removeObserver(self, forKeyPath: "localizedDescription")

        repeatsProgress.resignCurrent()
    }
}

最后一部分是KVO：

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?)
{
        guard context == &progressObservationContext else {
        super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
        return
    }

    if keyPath == "fractionCompleted"
    {
        OperationQueue.main.addOperation{
                let progress = object as! Progress
                self.repeatsSearchProgressBar.doubleValue = progress.fractionCompleted
                self.repeatsPercentText.stringValue = progress.localizedDescription
        }
    }
}

我增加了

print("Observed Something")

在

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?)
{  ...

我看到的是在启动后立即打印两次"Observed Something"，在结束时打印六次，中间没有打印(这是用于更新过程的预期)。原因是什么？

Answer 1

这似乎是一个并发问题。由于func actionFindRepeats(_ sender: AnyObject)在主线程中运行，所以它与UI更新同时进行，这直接影响到NSProgressIndicator。

有关此问题的更多详细信息，请参阅该答案的最后一个示例：

• https://stackoverflow.com/a/35810608/4370893

您可以尝试将actionFindRepeats函数的所有内容添加到该块中，并查看它是否有效：

DispatchQueue.global().async {
    // qos' default value is ´DispatchQoS.QoSClass.default`
}

该区块的参考资料：

• https://stackoverflow.com/a/37806522/4370893