我有一个简单的结构，我使用NSURLSession从Web获取数据。我想扩展它以提供下载进度。我不能使用struct作为NSURLSession委托，因为它需要是一个NSObject，所以我创建了一个简单的类，我传递给NSURLSession委托。这是我的代码的简短版本：
struct Resource {
private var progressDelegate: ProgressSessionDelegate?
private var session: NSURLSession!
init() {
self.progressDelegate = ProgressSessionDelegate()
let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
session = NSURLSession(configuration: configuration, delegate: self.progressDelegate!, delegateQueue: nil)
}
func loadAsynchronous(callback: A? -> ()) {
session.dataTaskWithURL(resourceURL) {
data, response, error in
let json = data.flatMap {
try? NSJSONSerialization.JSONObjectWithData($0, options: NSJSONReadingOptions())
}
callback(mycalback)
}.resume()
}
}
那就是我应该处理委托方法的cass：
class ProgressSessionDelegate: NSObject, NSURLSessionDelegate, NSURLSessionDataDelegate {
var expectedContentLength = 0
var currentLength = 0
override init() {
super.init()
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) {
expectedContentLength = Int(response.expectedContentLength)
print("0: \(expectedContentLength)")
completionHandler(NSURLSessionResponseDisposition.Allow)
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
self.currentLength += data.length
let percentageDownloaded = Float(self.currentLength) / Float(self.expectedContentLength)
print("1: \(percentageDownloaded)")
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
print("Downloaded")
}
}
问题是没有调用委托方法。
当我将代码从Resource和ProgressSessionDelegate结构移动到我的ViewController并将ViewController设置为NSURLSession委托时，一切正常。我认为问题在于如何存储类是struct。
任何帮助都将非常感激。