我有一个UITableView，其中的数据来自Firebase RealtimeDatabase。用户选择该行后，该行中的数据，即标题，说明和图像将被带到下一个ViewController。
我可以通过标题和说明，但不能通过图像。
这是我的UITableView代码：
import UIKit
import Firebase
class PostTable: UIViewController, UITableViewDelegate, UITableViewDataSource {
var tableView:UITableView!
var posts = [Post]()
override func viewDidLoad() {
super.viewDidLoad()
tableView = UITableView(frame: view.bounds, style: .plain)
view.addSubview(tableView)
let cellNib = UINib(nibName: "PostTableViewCell", bundle: nil)
tableView.register(cellNib, forCellReuseIdentifier: "postCell")
var layoutGuide:UILayoutGuide!
layoutGuide = view.safeAreaLayoutGuide
tableView.leadingAnchor.constraint(equalTo: layoutGuide.leadingAnchor).isActive = true
tableView.topAnchor.constraint(equalTo: layoutGuide.topAnchor).isActive = true
tableView.trailingAnchor.constraint(equalTo: layoutGuide.trailingAnchor).isActive = true
tableView.bottomAnchor.constraint(equalTo: layoutGuide.bottomAnchor).isActive = true
tableView.delegate = self
tableView.dataSource = self
tableView.tableFooterView = UIView()
tableView.reloadData()
observePosts()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func observePosts() {
let postsRef = Database.database().reference().child("Data")
print(postsRef)
postsRef.observe(.value, with: { snapshot in
var tempPosts = [Post]()
for child in snapshot.children{
if let childSnapshot = child as? DataSnapshot,
let dict = childSnapshot.value as? [String:Any],
let title = dict["title"] as? String,
let logoImage = dict["image"] as? String,
let url = URL(string:logoImage),
let description = dict["description"] as? String{
let userProfile = UserProfile(title: title, photoURL: url)
let post = Post(id: childSnapshot.key, title: userProfile, description: description, image: userProfile)
print(post)
tempPosts.append(post)
}
}
self.posts = tempPosts
self.tableView.reloadData()
})
}
func getImage(url: String, completion: @escaping (UIImage?) -> ()) {
URLSession.shared.dataTask(with: URL(string: url)!) { data, response, error in
if error == nil {
completion(UIImage(data: data!))
} else {
completion(nil)
}
}.resume()
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print(posts.count)
return posts.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
let cell = tableView.dequeueReusableCell(withIdentifier: "postCell", for: indexPath) as! PostTableViewCell
cell.set(post: posts[indexPath.row])
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let postsInfo = posts[indexPath.row]
print(postsInfo)
let Storyboard = UIStoryboard(name: "Main", bundle: nil)
let DvC = Storyboard.instantiateViewController(withIdentifier: "PostTableDetailed") as! PostTableDetailed
DvC.getName = postsInfo.title.title
DvC.getDesc = postsInfo.description
// DvC.getImg = postsInfo.title.photoURL
self.navigationController?.pushViewController(DvC, animated: true)
}
}
这是第二个ViewControler，其中包含帖子详细信息：
import UIKit
class PostTableDetailed: UIViewController {
var getName = String()
var getDesc = String()
@IBOutlet weak var Name: UILabel!
@IBOutlet weak var Description: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
Name.text! = getName
Description.text! = getDesc
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
我也有一些模型（Post，UserProfile）和服务（UserService和ImageService），请告诉我是否可以解决此问题。
答案 0 :(得分：1)
如果有imageUrl，则只需将其从PostTable传递到PostTableDetailed并下载图像。
// PostTable
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let postsInfo = posts[indexPath.row]
print(postsInfo)
let Storyboard = UIStoryboard(name: "Main", bundle: nil)
let DvC = Storyboard.instantiateViewController(withIdentifier: "PostTableDetailed") as! PostTableDetailed
DvC.getName = postsInfo.title.title
DvC.getDesc = postsInfo.description
DvC.getImg = postsInfo.photoURL
self.navigationController?.pushViewController(DvC, animated: true)
}
// PostTableDetailed
class PostTableDetailed: UIViewController {
var getName = String()
var getDesc = String()
var imageUrl = ""
@IBOutlet weak var Name: UILabel!
@IBOutlet weak var Description: UILabel!
@IBOutlet weak var imageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
Name.text! = getName
Description.text! = getDesc
updayeImage()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
private func updateImage() {
URLSession.shared.dataTask(with: URL(string: self.imageUrl)!) { data, response, error in
if error == nil, let data = data {
imageView.image = UIImage(data: data)
}
}.resume()
}
}
任务完成时将显示图像。 因此，建议您在imageView中添加微调器。
答案 1 :(得分：1)
在PostDetail ViewController中这样做
import UIKit
class PostTableDetailed: UIViewController {
var getName = String()
var getDesc = String()
var getImg = String()
@IBOutlet weak var Name: UILabel!
@IBOutlet weak var Description: UILabel!
@IBOutlet weak var ImageContainer: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
Name.text! = getName
Description.text! = getDesc
if let image = getImage(url: getImg) { (image)
ImageContainer.image = image
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func getImage(url: String, completion: @escaping (UIImage?) -> ()) {
URLSession.shared.dataTask(with: URL(string: url)!) { data, response, error in
if error == nil {
completion(UIImage(data: data!))
} else {
completion(nil)
}
}.resume()
}
}
答案 2 :(得分：0)
首先，您可以使用以下代码下载图像：
let imageCache = NSCache<AnyObject, AnyObject>()
extension UIImageView {
func downloadImageWithUrlString(urlString: String) -> Void {
if urlString.count == 0 {
print("Image Url is not found")
return
}
self.image = nil
if let cachedImage = imageCache.object(forKey: urlString as AnyObject) as? UIImage {
self.image = cachedImage
return
}
let request = URLRequest(url: URL(string: urlString)!)
let dataTask = URLSession.shared.dataTask(with: request) {data, response, error in
if error != nil { return }
DispatchQueue.main.async {
let downloadedImage = UIImage(data: data!)
if let image = downloadedImage {
imageCache.setObject(image, forKey: urlString as AnyObject)
self.image = UIImage(data: data!)
}
}
}
dataTask.resume()
}
}
现在，如果您正在使用包含Title，Description和ImageUrlString的模型，则只需将选定的模型对象传递给下一个viewController。
在下一个ViewController中，只需调用相同的方法来下载您在第一个ViewController上使用的图像。您无需将映像从VC1传递到VC2，因为它可能尚未下载映像，您可以选择一行以在下一个VC上移动。
因此，这里传递模型对象并调用图像下载方法的简单操作。