我的按钮代码从URL下载文件，我需要将其与进度视图链接以显示下载进度。
@IBAction func btnStream(sender: UIButton) {
// First you need to create your audio url
if let audioUrl = NSURL(string: "http://website.com/file.mp3") {
// then lets create your document folder url
let documentsUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL
// lets create your destination file url
let destinationUrl = documentsUrl.URLByAppendingPathComponent(audioUrl.lastPathComponent!)
println(destinationUrl)
// to check if it exists before downloading it
if NSFileManager().fileExistsAtPath(destinationUrl.path!) {
println("The file already exists at path")
// if the file doesn't exist
} else {
// just download the data from your url
if let myAudioDataFromUrl = NSData(contentsOfURL: audioUrl){
// after downloading your data you need to save it to your destination url
if myAudioDataFromUrl.writeToURL(destinationUrl, atomically: true) {
println("file saved")
} else {
println("error saving file")
}
}
}
}
}
如何将我的下载进度与Swift中的进度视图相关联？
答案 0 :(得分：6)
以下是完整的工作示例：
body您可以使用import UIKit
class ViewController: UIViewController, NSURLSessionDownloadDelegate {
@IBOutlet weak var progressBar: UIProgressView!
@IBOutlet weak var progressCount: UILabel!
var task : NSURLSessionTask!
var percentageWritten:Float = 0.0
var taskTotalBytesWritten = 0
var taskTotalBytesExpectedToWrite = 0
lazy var session : NSURLSession = {
let config = NSURLSessionConfiguration.ephemeralSessionConfiguration()
config.allowsCellularAccess = false
let session = NSURLSession(configuration: config, delegate: self, delegateQueue: NSOperationQueue.mainQueue())
return session
}()
override func viewDidLoad() {
progressBar.setProgress(0.0, animated: true) //set progressBar to 0 at start
}
@IBAction func doElaborateHTTP (sender:AnyObject!) {
progressCount.text = "0%"
if self.task != nil {
return
}
let s = "http://www.qdtricks.com/wp-content/uploads/2015/02/hd-wallpapers-1080p-for-mobile.png"
let url = NSURL(string:s)!
let req = NSMutableURLRequest(URL:url)
let task = self.session.downloadTaskWithRequest(req)
self.task = task
task.resume()
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten writ: Int64, totalBytesExpectedToWrite exp: Int64) {
println("downloaded \(100*writ/exp)")
taskTotalBytesWritten = Int(writ)
taskTotalBytesExpectedToWrite = Int(exp)
percentageWritten = Float(taskTotalBytesWritten) / Float(taskTotalBytesExpectedToWrite)
progressBar.progress = percentageWritten
progressCount.text = String(format: "%.01f", percentageWritten*100) + "%"
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didResumeAtOffset fileOffset: Int64, expectedTotalBytes: Int64) {
// unused in this example
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
println("completed: error: \(error)")
}
// this is the only required NSURLSessionDownloadDelegate method
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
let documentsDirectoryURL = NSFileManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL
println("Finished downloading!")
println(documentsDirectoryURL)
var err:NSError?
// Here you can move your downloaded file
if NSFileManager().moveItemAtURL(location, toURL: documentsDirectoryURL.URLByAppendingPathComponent(downloadTask.response!.suggestedFilename!), error: &err) {
println("File saved")
} else {
if let err = err {
println("File not saved.\n\(err.description)")
}
}
}
}
来实现此目的，当用户下载数据时，将调用其方法。
这将显示进入NSURLSessionDownloadDelegate标签的过程，progressCount将显示进程，因为计数将递增。你可以根据需要修改它。
您可以从HERE下载此示例。
答案 1 :(得分：2)
检查here。它位于Objective-C中，但很容易转换为Swift。
原则是在VC上实现一些Separator函数：
希望它有所帮助，如果您在将Obj-C转换为Swift时遇到麻烦，请不要犹豫。