我正在制作一个应用程序,您可以在其中使用 http://www.omdbapi.com/ 的 API 搜索电影.
我遇到的问题是 dataTaskWithRequest 的完成处理程序。如果您单击其中一个 collectionView 单元格,您将转到所选电影的 detailView。然而,它并不总是有效。我收到一条错误消息:展开时意外发现 nil。那是因为它没有进入 dataTaskWithRequest 的完成处理程序,而是直接进入 detailVC 并尝试在标题标签、流派标签等中传递数据,但没有数据。
我希望你们知道问题是什么,因为我已经尝试过但我没有看到问题是什么。
或者,这个问题是不是因为之前的事情导致的?因为首先我从 http://www.omdbapi.com/ 检索数据使用“按搜索”而不是“按 ID”。然后我从那里检索 ID,并从该 ID 检索我的 detailVC 的数据。
这是我的代码:
// Go to detail view of selected movie
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
let selectedMovieId = self.IDs[indexPath.row]
chosenMovieId = selectedMovieId
self.performSegueWithIdentifier("showDetail", sender: self)
}
// Preparations before going to the detail view of selected movie
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDetail" {
_ = self.movieInfoFrom(searchMovie: chosenMovieId, segue: segue)
}
}
func movieInfoFrom(searchMovie movieId: String, segue: UIStoryboardSegue) {
let movieUrlString = "http://www.omdbapi.com/?i=\(movieId)&y=&plot=full&r=json"
let url = NSURL(string: movieUrlString)
print(movieUrlString)
let urlRequest = NSURLRequest(URL: url!)
let urlSession = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
let urlTask = urlSession.dataTaskWithRequest(urlRequest) { (data, response, error) in
if error == nil {
// Convert data to JSON
let swiftyJSON = JSON(data: data!)
let title = swiftyJSON["Title"].string!
let runTime = swiftyJSON["Runtime"].string!
let genre = swiftyJSON["Genre"].string!
let plot = swiftyJSON["Plot"].string!
let rating = swiftyJSON["imdbRating"].string!
let year = swiftyJSON["Year"].string!
let poster = swiftyJSON["Poster"].string
self.infoResult = ["\(title)", "\(runTime)", "\(genre)", "\(plot)", "\(rating)", "\(year)"]
print("\(self.infoResult)")
let destinationVC = segue.destinationViewController as! MovieDetailController
destinationVC.movieDetails = self.infoResult
destinationVC.moviePoster = poster
}
}
urlTask.resume()
}
最佳答案
我尝试修复您的代码并用一些评论进行解释:
func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {
let selectedMovieId = self.IDs[indexPath.row]
chosenMovieId = selectedMovieId
self.movieInfoFrom(searchMovie: chosenMovieId)
}
// Preparations before going to the detail view of selected movie
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == "showDetail" {
let destinationVC = segue.destinationViewController as! MovieDetailController
destinationVC.movieDetails = self.infoResult
destinationVC.moviePoster = poster
}
}
func movieInfoFrom(searchMovie movieId: String) {
let movieUrlString = "http://www.omdbapi.com/?i=\(movieId)&y=&plot=full&r=json"
let url = NSURL(string: movieUrlString)
print(movieUrlString)
let urlRequest = NSURLRequest(URL: url!)
let urlSession = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration())
// This is asynchronously, you can put a loading here
let urlTask = urlSession.dataTaskWithRequest(urlRequest) { (data, response, error) in
// Got response, stop loading here
if error == nil {
// Convert data to JSON
let swiftyJSON = JSON(data: data!)
let title = swiftyJSON["Title"].string!
let runTime = swiftyJSON["Runtime"].string!
let genre = swiftyJSON["Genre"].string!
let plot = swiftyJSON["Plot"].string!
let rating = swiftyJSON["imdbRating"].string!
let year = swiftyJSON["Year"].string!
// You can save the poster as local variable
let poster = swiftyJSON["Poster"].string
self.infoResult = ["\(title)", "\(runTime)", "\(genre)", "\(plot)", "\(rating)", "\(year)"]
print("\(self.infoResult)")
// This should be call on main thread
dispatch_async(dispatch_get_main_queue()) {
self.performSegueWithIdentifier("showDetail", sender: self)
}
}
}
urlTask.resume()
}
关于ios - 带有请求完成处理程序的数据并不总是被调用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/37614893/