Question

如何在for循环之外返回public abstract class FilteringDemoDelegate { public abstract void ImageViewControllerDidFinish(UIImage filteredImage); } public class ImageViewController : UIViewController { UIImage sourceImage, displayImage, resultImage; public FilteringDemoDelegate filteringDelegate; UIButton saveButton, resetButton; UIImageView imageView; UISlider sliderC, sliderB; UILabel labelC, labelB; public ImageViewController(UIImage image) { sourceImage = image; } public override void ViewDidLoad() { base.ViewDidLoad(); Title = "Settings"; View.BackgroundColor = UIColor.White; resetButton = UIButton.FromType(UIButtonType.RoundedRect); resetButton.Frame = new CGRect(110, 40, 90, 40); resetButton.SetTitle("Reset", UIControlState.Normal); resetButton.SetTitleColor(UIColor.FromRGB(11, 132, 66), UIControlState.Normal); resetButton.TouchUpInside += (sender, e) => { sliderB.Value = 0; sliderC.Value = 1; HandleValueChanged(sender, e); }; View.Add(resetButton); saveButton = UIButton.FromType(UIButtonType.RoundedRect); saveButton.Frame = new CGRect(210, 40, 90, 40); saveButton.SetTitle("Save", UIControlState.Normal); saveButton.SetTitleColor(UIColor.FromRGB(11, 132, 66), UIControlState.Normal); saveButton.TouchUpInside += (sender, e) => { if (resultImage != null) { ImageEditingViewController(resultImage); } else { ImageEditingViewController(sourceImage); } }; View.Add(saveButton); labelC = new UILabel(new CGRect(10, 100, 90, 20)); labelB = new UILabel(new CGRect(10, 140, 90, 20)); labelC.Text = "Contrast"; labelB.Text = "Brightness"; View.Add(labelC); View.Add(labelB); sliderC = new UISlider(new CGRect(100, 100, 210, 20)); sliderB = new UISlider(new CGRect(100, 140, 210, 20)); sliderC.MinValue = 0; sliderC.MaxValue = 4; sliderC.Value = 1; sliderB.MinValue = -1; sliderB.MaxValue = 1; sliderB.Value = 0; // update the image in 'real time' as the sliders are moved sliderC.ValueChanged += HandleValueChanged; sliderB.ValueChanged += HandleValueChanged; View.Add(sliderC); View.Add(sliderB); imageView = new UIImageView(new CGRect(10, 200, View.Bounds.Width - 20, View.Bounds.Height - 200)); displayImage = sourceImage; imageView.Image = displayImage; View.Add(imageView); } void HandleValueChanged(object sender, EventArgs e) { // use the low-res version imageView.Image = AdjustImage(displayImage); if (resultImage != null) { resultImage.Dispose(); } resultImage = imageView.Image; } CIContext context; CIColorControls colorCtrls; //CIFilter UIImage AdjustImage(UIImage image) { if (colorCtrls == null) colorCtrls = new CIColorControls() { Image = CIImage.FromCGImage(image.CGImage) }; else colorCtrls.Image = CIImage.FromCGImage(image.CGImage); if (context == null) context = CIContext.FromOptions(null); colorCtrls.Contrast = (float)Math.Round(sliderC.Value, 1); colorCtrls.Brightness = (float)Math.Round(sliderB.Value, 1); using (var outputImage = colorCtrls.OutputImage) { var result = context.CreateCGImage(outputImage, outputImage.Extent); return UIImage.FromImage(result); } } public void ImageEditingViewController(UIImage filteredImage) { if (filteringDelegate != null) { filteringDelegate.ImageViewControllerDidFinish(filteredImage); } DismissViewController(false, null); } }的值。我需要进行api调用stuff次，并且每次都存储结果。答案中可能存在重复的问题，但我无法找到答案。

我试过让这个函数只进行1次调用，然后在另一个调用此函数的函数中循环，但我得到function getResponse() { var stuff = [] for (let i = 0; i < length; i++) { axios.get(url + i) .then(res => res.forEach(item => { stuff.push(item) })) } // How do I return stuff from this function ? } console.log(getResponse())。

Answer 1

如何从此功能返回内容？

你做不到。它就像“我想得到明天的报纸”。这也行不通。您必须等到第二天才能阅读报纸，或者在您的情况下，直到所有数据都到达浏览器。您不能直接返回数据，而是一个 Promise ，它将在某些时候提供数据。在您的情况下，您可以使用Promise.all将一组promises统一为一个解析为数组的promise：

function getResponse() {
  const promises = [];

  for (let i = 0; i < length; i++) {
    promises.push(axios.get(url + i));
  }

  return Promise.all(promises)
    .then(results => [].concat(...results));
}

现在如果你这样做：

console.log(getResponse())

你得到了承诺。要获取实际数据，您必须等到数据到达：

getResponse().then(console.log);

在axios异步调用之外返回数据

1 个答案: