整个应用程序在快速加载图片时出现滞后

Question

你好，当我从服务器加载图片时，我的应用程序滞后了。如果没有大量延迟，我无法滚动或转到下一个视图控制器。我试着用DispatchQueue.main.async和OperationQueue,main.addQueue在DispatchQueue方法中，我不能做任何事情，只能等待。在左侧，我可以看到最后一个视图控制器的一部分。

这是我的代码

func fetchData(uiView: UIView) {
        let urlString = URL(string: "https://mydomain/assats/php/Random.php")!
         let task = URLSession.shared.dataTask(with: urlString) { (data, response, error) in
            guard let data = data, error == nil else {
                debugPrint("Fehler beim Laden von (urlString)", String(describing: error))
                return
            }
                   let JSONData = try? JSONDecoder().decode([Pics].self, from: data)
            OperationQueue.main.addOperation {
                let currentWidthScroll: Int = (100 / 1) - (100 / 1) + (1 * 0) + (1 * 0) + 0
                        let currentHighScroll: Int = (100 / 1) - (100 / 1) + (1 * 100) + (1 * 5) + 21
                        let screensize: CGRect = UIScreen.main.bounds
                        let screenWidth = screensize.width
                        let screenHeight = screensize.height
                        var scrollView = UIScrollView()
                            scrollView = UIScrollView(frame: CGRect(x: CGFloat(currentWidthScroll), y: CGFloat(currentHighScroll), width: screenWidth, height: screenHeight))
                             self.view.addSubview(scrollView)
                if JSONData == nil {
                    let alert = UIAlertController(title: "Error", message: "You can't see much here because you don't Follow anybody", preferredStyle: .alert)
                    
                    alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
                    self.present(alert, animated: true)
                }
                              
                else {
                    
                   for x in 0..<JSONData!.count {
                        OperationQueue.main.addOperation {
                            print(x)
                    
                            
                       let currentWidth: Int = (100 / 1) - (100 / 1) + (x * 0) + (x * 0) + 10
                                   
                         let currentHigh: Int = (100 / 1) - (100 / 1) + (x * 500) + (x * 5) + 80
                         let stackView = UIStackView(frame: CGRect(x: CGFloat(currentWidth), y: CGFloat(currentHigh), width: 350, height: 500))
                    
                                   
                         stackView.alignment = .fill
                         stackView.distribution = .fillEqually
                         stackView.axis = .vertical
                        scrollView.contentSize = CGSize(width: 0, height: currentHigh + 650)
                        scrollView.addSubview(stackView)
                    
                    
                   let urlKey = "http://instapy.ddns.net/User/(JSONData![x].Benutzername)/Posts/Photos/(JSONData![x].Pic)"
                    let imgView = UIImageView(frame: CGRect(x: CGFloat(currentWidth), y: CGFloat(currentHigh), width: 350, height: 500))
                    imgView.image = UIImage(named: urlKey)
                    imgView.contentMode = .scaleAspectFit
                    stackView.addArrangedSubview(imgView)
                    
                       if let url = URL(string: urlKey) {
                           
                       do{
                            let data = try Data(contentsOf: url)
                           imgView.image = UIImage(data: data)
                           }catch let err {
                           print("Error: (err.localizedDescription)")
                            }
                        }
                    }
                    }
                }
            }
        };task.resume()
    }

我在viewDidLoad((中加载函数

Answer 1

问题在这里

 let data = try Data(contentsOf: url)

上面的行不应该在主队列中，因为它会阻止它，我想你需要一个tableView而不是scrollView+stackView，并最好通过SDWebImage 加载带有URL的图像