我目前正在尝试为显示图像以及其他信息的应用程序设计新闻源。我可以从我们的mySQL数据库中获取URL，但是当我尝试下载它时，我收到一条错误，说“致命错误：在展开可选值时意外发现nil”，尽管提供了这段代码：
if let imageData = data {
let pic = UIImage(data: imageData)
print()
cell.activityImage.image = pic
self.images.append(pic!)
}
非可选字符串。这是整个代码
class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
var activities = [AnyObject]()
var images = [UIImage]()
@IBOutlet var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
//tableView.contentInset = UIEdgeInsetsMake(2, 0, 0, 0)
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return activities.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "activity", for: indexPath) as! CustomCell
let post = activities[indexPath.row]
//print(post["path"])
//let image = images[indexPath.row]
let imaged = post["path"] as! String
//print(imaged)
let image = URL(string: imaged)! //download url
print(image)
let username = post["username"] as? String
let text = post["text"] as? String
let session = URLSession(configuration: .default)
let downloadPicTask = session.dataTask(with: image) {
(data, response, error) in
if let e = error {
print("Error downloading image: \(e)")
} else {
if (response as? HTTPURLResponse) != nil {
if let imageData = data {
let pic = UIImage(data: imageData)
print()
cell.activityImage.image = pic
self.images.append(pic!)
} else{
print("couldn't get image: image is nil")
}
} else {
print("Couldn't get response code")
}
}
}
cell.titleLabel.text = text
cell.usernameLabel.text = username
downloadPicTask.resume()
return cell
}
override func viewWillAppear(_ animated: Bool) {
loadActivities()
}
func loadActivities() {
let id = user!["id"] as! String
let url = URL(string: "https://cgi.soic.indiana.edu/~team7/posts.php")!
var request = URLRequest(url: url)
request.httpMethod = "POST"
let body = "id=\(id)&text=&uuid="
request.httpBody = body.data(using: String.Encoding.utf8)
URLSession.shared.dataTask(with: request) { data, response, error in
DispatchQueue.main.async(execute: {
if error == nil {
do {
let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as? NSDictionary
self.activities.removeAll(keepingCapacity: false)
self.images.removeAll(keepingCapacity: false)
self.tableView.reloadData()
guard let parseJSON = json else {
print("Error while parsing")
return
}
guard let posts = parseJSON["posts"] as? [AnyObject] else {
print("Error while parseJSONing")
return
}
self.activities = posts
for i in self.activities.indices {
let path = self.activities[i]["path"] as? String
if let actualPath = path, !actualPath.isEmpty, let url = URL(string: actualPath) {
if let imageData = try? Data(contentsOf: url) {
if let image = UIImage(data: imageData) {
self.images.append(image)
print(self.images)
}
}
}
/*
if path != "" {
//let url = URL(string: path!)!
let url = URL(fileURLWithPath: path!)
let imageData = try? Data(contentsOf: url)
//let imageData = try? Data(contentsOf: url)
let image = UIImage(data: imageData!)!
self.images.append(image)
*/
else {
let image = UIImage()
self.images.append(image)
}
}
self.tableView.reloadData()
} catch {
}
} else {
}
})
}.resume()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
extension NSMutableData {
func appendString(_ string : String) {
let data = string.data(using: String.Encoding.utf8, allowLossyConversion: true)
append(data!)
}
}
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