Ios 使用Swift和Parse创建图像预览

我目前正在用Swift编写一个社交网络应用程序。在我的应用程序中，我有一个功能，用户可以向时间线发送带有图像的消息。我希望能够检索图像并使用时间线内的UIImageView预览它。但是，我希望图像显示在发送图像的用户旁边，如果用户未发布图像，则图像预览不会与消息一起显示。我想要的一个很好的例子是Facebook和Twitter在各自的iOS应用程序中显示图像的方式。同时，我编写了以下函数来检索图像，但是我在匹配正确的用户时遇到了问题。我将有我的功能张贴在下面，以及链接下载源代码到我的时间表。提前谢谢

func loadImages（）

---

我在这门课上做到了：

import UIKit
import Parse

class postViewController: UIViewController, UINavigationControllerDelegate, UIImagePickerControllerDelegate {

    var photoSelected:Bool = false
    var activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView()

    @IBOutlet weak var imageToPost: UIImageView!
    @IBOutlet weak var shareText: UITextField!

    @IBAction func logout(sender: AnyObject) {
        PFUser.logOut()
        self.performSegueWithIdentifier("logout", sender: "self")
    }   

    @IBAction func chooseImage(sender: AnyObject) {
        // Creation d'une variable image controlleur
        var image = UIImagePickerController()
        dispatch_async(dispatch_get_main_queue()){
        image.delegate = self
        image.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
        image.allowsEditing = false

            self.presentViewController(image, animated: true, completion: nil)}
    }

    @IBAction func postImage(sender: AnyObject) {
        var error = ""
        if (photoSelected == false){
            error = "Please Select an Image to post"
        } else if (shareText.text == "") {
            error = "Please enter a message"
        }
        if (error != ""){
            displayAlert("Cannot post Image", error: error)
        } else {

            activityIndicator = UIActivityIndicatorView(frame: CGRectMake(0, 0, 50, 50))
            // On positione l'indicateur au centre de l'ecran
            activityIndicator.center = self.view.center
            activityIndicator.hidesWhenStopped = true
            activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.Gray
            view.addSubview(activityIndicator)
            activityIndicator.startAnimating()
            UIApplication.sharedApplication().beginIgnoringInteractionEvents()

            var post = PFObject(className: "post")
            post["Title"] = shareText.text
            post["username"] = PFUser.currentUser().username

            post.saveInBackgroundWithBlock{(success: Bool, error: NSError!) -> Void in

                if success == false {
                    self.activityIndicator.stopAnimating()
                    UIApplication.sharedApplication().endIgnoringInteractionEvents()

                    self.displayAlert("Could not post Image", error: "Please try again later")

                } else {

                    let imageData = UIImagePNGRepresentation(self.imageToPost.image)
                    let imageFile = PFFile(name: "image.png", data: imageData)

                    post["imageFile"] = imageFile
                    post.saveInBackgroundWithBlock{(success: Bool, error: NSError!) -> Void in

                        self.activityIndicator.stopAnimating()
                        UIApplication.sharedApplication().endIgnoringInteractionEvents()

                        if success == false {

                            self.displayAlert("Could not post Image", error: "Please try again later")
                        } else {
                            self.displayAlert(" Image Posted !", error: "Your image has been posted successfully")
                            self.photoSelected = false
                            self.imageToPost.image = UIImage(named: "default-placeholder")
                            self.shareText.text = ""
                            println("Posted succesfully")
                        }
                    }
                }
            }
        }
    }

    func displayAlert(title: String, error: String){
        var alert = UIAlertController(title: title, message: error, preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: {action in
            }))
            self.presentViewController(alert, animated: true, completion: nil)
    }

    func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
        println("Image is selected!")
        self.dismissViewControllerAnimated(true, completion: nil)

        imageToPost.image = image

        photoSelected = true
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        photoSelected = false

        imageToPost.image = UIImage(named: "default-placeholder")

        self.shareText.text = ""
    }

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

    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        self.view.endEditing(true)
    }


    func textFiledShouldReturn(textField: UITextField!) -> Bool{
        shareText.resignFirstResponder()
        return true
    }
}

编辑：

您可以添加如下测试：

func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {

        self.dismissViewControllerAnimated(true, completion: nil)
        initialisationPhoto()

        photoUtilisateur.image = image

        if (photoUtilisateur.image != nil){
            println("Image is selected!")
            photoSelected = true
        }
    }

func initialisationPhoto(){
    //Initialisation de la photo utilisateur
    photoSelected = false
    photoUtilisateur.image = UIImage(named: "placeholder")
}

---

谢谢你的密码。我取了一些并添加到我的类中，但是在调用图像选择器函数时遇到了一个可选值的问题。我已经在下面发布了我的代码。你知道怎么修理吗？func imagePickerController（picker:UIImagePickerController！、didFinishPickingImage:UIImage！、editingInfo:[NSObject:AnyObject]！）{println（“选择的图像”）self.dismissViewControllerAnimated（true，completion:nil）ImagetoPost.image！=图像//错误此处photoSelected=true}我已经编辑了我的答案，查看imagePickerController函数中的测试：）这是我的代码在测试函数中仍然出现错误的屏幕截图。我做错了什么？嗯，你想用模拟器拍照吗？因为你只能用设备拍照。使用模拟器，您只能从照片库中获取照片。这是您的问题吗？是的，当我在物理设备上拍照时，当a在模拟器中选择照片时，会发生错误。只要你点击“使用照片”按钮，应用程序就会崩溃。

func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {

        self.dismissViewControllerAnimated(true, completion: nil)
        initialisationPhoto()

        photoUtilisateur.image = image

        if (photoUtilisateur.image != nil){
            println("Image is selected!")
            photoSelected = true
        }
    }

func initialisationPhoto(){
    //Initialisation de la photo utilisateur
    photoSelected = false
    photoUtilisateur.image = UIImage(named: "placeholder")
}