Swift：UILabel和UIImageView加載8-30秒

我是Swift開發新手，現在我完全失去了。我製作了一個簡單的標籤並將其放置在Storyboard上。我的代碼根本沒有與它進行交互，但加載需要8-30秒，與默認情況下放置的其他UILabel不同。爲什麼是這樣？Swift：UILabel和UIImageView加載8-30秒

我對從URL獲取的圖像有同樣的問題。它立即下載圖像並將其分配給UIImageView，但實際更新需要8-30秒，而我不知道爲什麼。

這裏是我的控制器代碼 FirstViewController.swift

import UIKit 

class FirstViewController: UIViewController { 
    @IBOutlet var profilePicture: UIImageView! 
    var currentUser: User! 
    @IBOutlet var profileText: UILabel! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     // Declare currentUser variable 
     currentUser = User(email: "", first_name: "", last_name: "", department: "", admin: false, superadmin: false, thumb_url: "") 

     // Load timesheet structs 
     getTimesheetPages() 

     // Load user struct and wait for it to finish 
     getUserDetails() { 
      self.downloadProfilePic() 
     } 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
     // Dispose of any resources that can be recreated. 
    } 

    func downloadProfilePic() { 
     let regURL = "http://localhost:3000" 
     let profilePicURL = URL(string: regURL + currentUser.thumb_url)! 

     let session = URLSession(configuration: .default) 

     // Define a download task 
     let downloadPicTask = session.dataTask(with: profilePicURL) { (data, response, error) in 
      // The download has finished. 
      if let e = error { 
       print("Error downloading profile picture: \(e)") 
      } else { 
       // No errors found. 
       if let res = response as? HTTPURLResponse { 
        print("Downloaded profile picture with response code \(res.statusCode)") 
        if let imageData = data { 
         print("Enters image load") 

         // Finally convert that Data into an image and do what you wish with it. 
         let image = UIImage(data: imageData) 

         // Do something with your image. 
         self.profilePicture.image = image 

         // Initialize profile picture properties 
         self.profilePicture.layer.borderWidth = 1.0 
         self.profilePicture.layer.masksToBounds = false 
         self.profilePicture.layer.borderColor = UIColor.white.cgColor 
         self.profilePicture.layer.cornerRadius = self.profilePicture.frame.size.width/2 
         self.profilePicture.clipsToBounds = true 

        } else { 
         print("Couldn't get image: Image is nil") 
        } 
       } else { 
        print("Couldn't get response code for some reason") 
       } 
      } 
     } 

     downloadPicTask.resume() 
    } 

// more functions

以下是我與

在這裏工作的形象是我的仿真器顯示爲第一到10秒

來源

2017-05-25 Holabola

你的UI更新需要被分派到主線程 – dan

你怎麼在這？我將它包裝在DispatchQueue.main.async {}中，不起作用。 main.sync也不起作用。 – Holabola

'DispatchQueue.main.async {self.profilePicture.image = image; // UI更新代碼的其餘部分 }' –

正如利奧所說，我包裝了我的整個函數調用DispatchQueue.main.async { }而不是隻是UI更新電話。

通過改變self.profilePicture.image = image到

DispatchQueue.main.async { 
    self.profilePicture.image = image 
    // rest of UI update code 
}

它工作得十分完美

來源

2017-05-25 20:32:56 Holabola

Swift：UILabel和UIImageView加載8-30秒

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