为什么我在下载到同一条路径时获得不同的图像？

时间：2017-12-20 01:31:25

标签： ios swift image

我正在尝试调试用于上传图像的一大块代码，并从我自己的服务器下载该图像。

图片路径为“http://localhost/Twitter/Avatar/52/avatar.jpeg”

enter image description here

我们可以看到，该文件夹中有两个图像，相同的图像但名称不同。当我在下载图像时对路径进行硬编码时，我得到了一个奇怪的结果

 if avatarPath != nil {

        let x = "http://localhost/Twitter/Avatar/52/avatar.jpeg"

        let imageURL = URL(string: x)
        let session = URLSession(configuration: .default)
        let task = session.dataTask(with: imageURL!, completionHandler: { (data, response, error) in

            DispatchQueue.main.async {

                if let imageData = data {
                    self.avatarImage.image = UIImage(data: imageData)
                }
            }

        })

        task.resume()
    }



    // round courner of avatar
    avatarImage.layer.cornerRadius = avatarImage.bounds.width/20
    avatarImage.clipsToBounds = true

    //Give title to navigation controller
    self.navigationItem.title = username.uppercased()



    activityIndicator.stopAnimating()



}

当我写x =“http://localhost/Twitter/Avatar/52/pogba.jpeg”

时

我和路径的图像相同，就像这样

enter image description here

但当我改为让x =“http://localhost/Twitter/Avatar/52/avatar.jpeg”

时

我有不同的形象，就像这样

enter image description here

我第一次上传图片时曾经使用过该图片，但我不知道为什么该图片会再次出现。我还没有实现缓存图像。为什么会这样？

这是完整的源代码

import UIKit

class HomepageVC: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate {


@IBOutlet weak var avatarImage: UIImageView!
@IBOutlet weak var usernameLabel: UILabel!
@IBOutlet weak var fullnameLabel: UILabel!
@IBOutlet weak var emailLabel: UILabel!
@IBOutlet weak var editAvatarButton: UIButton!
@IBOutlet weak var activityIndicator: UIActivityIndicatorView!



override func viewDidLoad() {
    super.viewDidLoad()

    activityIndicator.startAnimating()

    // mendeklarasikan variable user yang berasal dari superglobal variable di appdelegate
    let username = userInfo?["username"] as! String
    let fullname = userInfo?["fullname"] as! String
    let email = userInfo?["email"] as! String
    let avatarPath = userInfo?["avatar"] as? String


    // update user interface text & Label
    usernameLabel.text = username.uppercased()
    fullnameLabel.text = fullname.capitalized
    emailLabel.text = email



    // update user interface avatar

    if avatarPath != nil {

        let x = "http://localhost/Twitter/Avatar/52/pogba.jpeg"

        let imageURL = URL(string: x)
        let session = URLSession(configuration: .default)
        let task = session.dataTask(with: imageURL!, completionHandler: { (data, response, error) in

            DispatchQueue.main.async {

                if let imageData = data {
                    self.avatarImage.image = UIImage(data: imageData)
                }
            }

        })

        task.resume()
    }



    // round courner of avatar
    avatarImage.layer.cornerRadius = avatarImage.bounds.width/20
    avatarImage.clipsToBounds = true

    //Give title to navigation controller
    self.navigationItem.title = username.uppercased()



    activityIndicator.stopAnimating()



}





@IBAction func logoutButtonDidPressed(_ sender: Any) {

    //menghapus data userDefault yang sudah ada
    UserDefaults.standard.removeObject(forKey: "parsedJSON")
    UserDefaults.standard.synchronize()

    //menuju ke login page dengan modal segue
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let loginVC = storyboard.instantiateViewController(withIdentifier: "loginVC")
    present(loginVC, animated: true, completion: nil)

}



@IBAction func editProfilePictureButtonDidPressed(_ sender: Any) {

    // user akan memilih photo dari library atau dari camera nya


    let imagePickerController = UIImagePickerController()
    imagePickerController.delegate = self
    imagePickerController.allowsEditing = true



    let actionSheet = UIAlertController(title: "Photo Source", message: "please choose your source", preferredStyle: .actionSheet)


    // action camera
    let actionCamera = UIAlertAction(title: "Camera", style: .default) { (action) in

        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            imagePickerController.sourceType = .camera
            self.present(imagePickerController, animated: true, completion: nil)

        } else {
            self.showAlert(alertTitle: "Opppss", alertMessage: "camera can't be used / not available", actionTitle: "OK")
            print("camera can't be used / not available")
        }

    }


    // action photo library
    let actionPhotoLibrary = UIAlertAction(title: "Photo Library", style: .default) { (action) in
        imagePickerController.sourceType = .photoLibrary
        self.present(imagePickerController, animated: true, completion: nil)
    }


    //action cancel
    let actionCancel = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)


    actionSheet.addAction(actionCamera)
    actionSheet.addAction(actionPhotoLibrary)
    actionSheet.addAction(actionCancel)


    self.present(actionSheet, animated: true, completion: nil)



}






func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {


    let image = info[UIImagePickerControllerOriginalImage] as! UIImage
    avatarImage.image = image
    picker.dismiss(animated: true, completion: nil)



    // call func of uploading file to server
    uploadAvatar()

}




func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
    picker.dismiss(animated: true, completion: nil)
}






// custom HTTP request body to upload image file
func createBodyWithParams(_ parameters: [String: String]?, filePathKey: String?, imageDataKey: Data, boundary: String) -> Data {

    var body = Data();

    if parameters != nil {
        for (key, value) in parameters! {
            body.appendString("--\(boundary)\r\n")
            body.appendString("Content-Disposition: form-data; name=\"\(key)\"\r\n\r\n")
            body.appendString("\(value)\r\n")
        }
    }

    // kita set agar image yang di upload kemudian berformat .jpg
    let filename = "avatar.jpeg"

    let mimetype = "image/jpeg"

    body.appendString("--\(boundary)\r\n")
    body.appendString("Content-Disposition: form-data; name=\"\(filePathKey!)\"; filename=\"\(filename)\"\r\n")
    body.appendString("Content-Type: \(mimetype)\r\n\r\n")
    body.append(imageDataKey)
    body.appendString("\r\n")

    body.appendString("--\(boundary)--\r\n")

    return body as Data

}


// uploading image ke server
func uploadAvatar() {



    // mendapatkan ID dari User Default variable
    let id = userInfo!["id"] as! String


    // membuat request
    let url = URL(string: "http://localhost/Twitter/uploadAvatar.php")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"


    // parameter yang akan dikirim di dalam request body
    // parameter ini dibutuhkan karena uploadAvatar.php membutuhkan inputan ID
    let param = ["id" : id]

    // membuat Boundary
    let boundary = "Boundary-\(UUID().uuidString)"
    request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")


    // mengassign image yang akan di upload dan melakukan kompresi
    let imageData = UIImageJPEGRepresentation(avatarImage.image!, 0.5)

    // if not compressed, return ... do not continue to code
    if imageData == nil {
        return
    }





    // constructing http body
    request.httpBody = createBodyWithParams(param, filePathKey: "file", imageDataKey: imageData!, boundary: boundary)

    // filePathKey berupa 'file' agar nanti di PHP $_FILES bisa didentifikasi, contohnya $_FILES['file'][tmp_name]


    // launc session
    URLSession.shared.dataTask(with: request) { data, response, error in




        DispatchQueue.main.async(execute: {

            if error == nil {

                // maka tampilkan $returnArray dari PHP (response message from server)

                do {

                    // json containes $returnArray from php
                    let json = try JSONSerialization.jsonObject(with: data!, options: []) as? NSDictionary

                    // declare new parseJSON to store json
                    guard let parsedJSON = json else {
                        print("Error while parsing")
                        return
                    }


                    print(parsedJSON)

                    // get id from $returnArray["id"] in PHP - parseJSON["id"]
                    let id = parsedJSON["id"]

                    // successfully uploaded
                    if id != nil {

                        // save user information yang berasal dari server
                        UserDefaults.standard.set(parsedJSON, forKey: "parsedJSON")
                        userInfo = UserDefaults.standard.object(forKey: "parsedJSON") as? NSDictionary





                        // jika tidak ada "id" kiriman dari server, maka ada error message
                    } else {

                        // get main queue to communicate back to user
                        DispatchQueue.main.async(execute: {
                            let message = parsedJSON["message"] as! String
                            self.showAlert(alertTitle: "opppps", alertMessage: message, actionTitle: "OK")
                        })

                    }



                    // error ketika melakukan JSON serialization
                } catch {

                    // get main queue to communicate back to user
                    DispatchQueue.main.async(execute: {
                        let message = error.localizedDescription
                        self.showAlert(alertTitle: "SorryBroooo", alertMessage: message, actionTitle: "OK")
                    })

                }

                // error ketika koneksi ke server
            } else {

                // get main queue to communicate back to user
                DispatchQueue.main.async(execute: {
                    let message = error!.localizedDescription
                    self.showAlert(alertTitle: "oppps", alertMessage: message, actionTitle: "OK")
                })

            }


        })

        }.resume()


}






}







    // extend data
    extension Data {

        mutating func appendString(_ string : String) {

            let data = string.data(using: String.Encoding.utf8, allowLossyConversion: true)
            append(data!)

        }

    }

1 个答案:

答案 0 :(得分：1)

使用此代码时

let session = URLSession(configuration: .default)

您已自动注册默认缓存策略，它使用此链接中指定的基于永久磁盘的缓存： https://developer.apple.com/documentation/foundation/urlsessionconfiguration/1411560-default

如果要删除所有缓存策略，请改用此代码

let session = URLSession(configuration: .ephemeral)
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