使用 Swift 和 Parse 创建图像预览

Question

我目前正在 Swift 中编写社交网络应用程序。在我的应用程序中，我有一个功能，即用户可以将带有图像的消息发送到时间轴。我希望能够检索图像并使用我的时间线内的 UIImageView 预览它。但是，我希望图像显示在发送图像的用户旁边，如果用户没有 post 图像，则图像预览不会与消息一起显示。我想要的功能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。与此同时，我编写了以下函数来检索图像，但我无法将它们与正确的用户匹配。我将在下面 posted 以及 link 将源代码下载到我的时间线。提前致谢

func loadImages()

    {
        var query = PFQuery(className: "imagesUploaded")
        query.orderByDescending("objectId")
        query.whereKey("user", equalTo:PFUser.currentUser())


        query.findObjectsInBackgroundWithBlock {
            (objects:[AnyObject]!,error:NSError!) -> Void in
            if error == nil {
                let imagesobjects = objects as [PFObject]

                for object : PFObject in objects as [PFObject] {
                    let image = object["filename"] as PFFile

                    image.getDataInBackgroundWithBlock {
                        (imageData:NSData!, error:NSError!) -> Void in
                        if error == nil {
                            if let finalimage = UIImage(data: imageData)
                            {
                                let url = image.url
                                println(url)
                                cell.imagedisplay.image = finalimage



                            }
                        }

                    }
                }
            }
        }
        }

TimeLine Source Code

Answer 1

我用这个 class :

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：

您可以像这样添加测试：

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")
}

使用 Swift 和 Parse 创建图像预览

Creating Image Preview using Swift and Parse

iphone

uiimage

ios

parse-platform

swift