URLSession Reloaded

Tips and tricks how to use URLSessionDownloadTask and it's utility class ZDownloader and it's sample project/code Image Downloader.

Transcript

1. NSURLSession
 Reloaded Yokohama iOS Developers Meeting Nov. 2016 Kaz Yoshikawa kyoshikawa@electricwoods.com
2. URLSession Reloaded About me
3. Kaz Yoshikawa • Electricwoods LLC ୅ද / Digital Lynx Systems Inc. ෭୅ද • e-mail: kyoshikawa@electricwoods.com • twitter: @codelynx1 • Working History • Adobe Systems (Tokyo) • Lionbridge (Tokyo) • Quark (Tokyo / Denver) • Hummingbird Communications (Mt. View, USA) • Fact International (Vancouver, Canada) • Perle Systems (Toronto, Canada), etc.
4. URLSession Reloaded What do you use for downloading?
5. URLSession Reloaded Downloading Options • CFNetwork • AFNetworking • Alamofire • NSOperation or GCD + NSData(contentsOf:) * • NSURLSession + NSURLSessionTask * or equivalent
6. URLSession Reloaded Alamofire vs URLSession left Intentionally blank
7. URLSession Reloaded URLSessionTask
8. URLSession Reloaded URLSessionTask URLSessionDataTask URLSessionDownloadTask URLSessionUploadTask
9. URLSession Reloaded URLSessionDataTask left Intentionally blank
10. URLSession Reloaded URLSessionDownloadTask • Downloads in foreground or background • download continues while app is killed or sleeping • Callback closure is useless — if app is killed by system • Use delegate method to catch up what have been downloaded
11. URLSession Reloaded Download Task Code DMBTT
    .Z$POUFOUT
    /40CKFDU
    63-4FTTJPO%PXOMPBE%FMFHBUF
    \
    
    
    
    
    GVOD
    VSM4FTTJPO @
    TFTTJPO
    63-4FTTJPO
    EPXOMPBE5BTL
    63-4FTTJPO%PXOMPBE5BTL
    

    
    
    
    
    
    
    
    
    
    
    
    EJE'JOJTI%PXOMPBEJOH5P
    MPDBUJPO
    63-
    \
    
    
    
    
    
    
    
    
    
    TBWF
    PS
    QSPDFTT
    EPXOMPBEFE
    GJMF
    
    
    
    
    ^
    
    
    
    GVOD
    VSM4FTTJPO @
    TFTTJPO
    63-4FTTJPO
    UBTL
    63-4FTTJPO5BTL
    

    
    
    
    
    
    
    
    
    
    
    
    EJE$PNQMFUF8JUI&SSPS
    FSSPS
    &SSPS
    \
    
    
    
    
    
    
    
    
    
    FSSPS
    IBOEMJOH
    
    ^
    ^
    MFU
    NZ$POUFOUT
    
    .Z$POUFOUT
    MFU
    DPOGJHVSBUJPO
    
    63-4FTTJPO$POGJHVSBUJPOCBDLHSPVOE 

    
    
    
    
    
    
    
    XJUI*EFOUJGJFS
    NZDPOUFOUT
    DPOGJHVSBUJPOBMMPXT$FMMVMBS"DDFTT
    
    GBMTF
    MFU
    TFTTJPO
    
    63-4FTTJPO DPOGJHVSBUJPO
    DPOGJHVSBUJPO
    
    
    
    
    
    
    
    
    EFMFHBUF
    NZ$POUFOUT
    EFMFHBUF2VFVF
    OJM
    MFU
    UBTL
    
    TFTTJPOEPXOMPBE5BTL XJUI
    63- TUSJOH
    IUUQBQQMFDPN 
    UBTLSFTVNF
12. URLSession Reloaded Case Study News App
13. URLSession Reloaded News Type of App catalog features sports economy article article current affairs photo photo download ads ads
14. URLSession Reloaded List of Contents (< 1MB) catalog features sports economy article article current affairs photo photo * * total ads ads
15. URLSession Reloaded Data Task catalog features sports economy article article current affairs photo photo ads ads
16. URLSession Reloaded Contents (>10MB) catalog features sports economy article article current affairs photo photo * total * ads ads
17. URLSession Reloaded Download Task catalog features sports economy article article current affairs photo photo ads ads
18. URLSession Reloaded Download Task catalog features sports economy article article current affairs photo photo ads ads
19. URLSession Reloaded How to identify the client of downloaded binary?
20. URLSession Reloaded URLSessionDownloadDelegate func urlSession(_ session: URLSession, 
 downloadTask: URLSessionDownloadTask, 
 didFinishDownloadingTo location: URL) How do I know which article or photo or ad is about this download !? Check the URL ☹ No way !!
21. URLSession Reloaded URLSessionTask
22. URLSession Reloaded taskIdentifier let url = URL(string: "https://www.apple.com")! let task = session.dataTask(with: url) { (data, response, error) in if let data = data { print(data as NSData) } } task.resume() task.taskIdentifier // task-id Integer • Needs keep this ID associate with article-id or other id • May be similar to use URL to identify the download owner • If you have other sessions, the ID may collide
23. URLSession Reloaded taskDescription • What you want to save here? • article-id?, path to save file?, managed object ID? • But this property is just a string let url = URL(string: "https://www.apple.com")! let task = session.dataTask(with: url) { (data, response, error) in if let data = data { print(data as NSData) } } task.taskDescription = "Some useful information"
 task.resume() String
24. URLSession Reloaded You underestimate the power of String..
25. URLSession Reloaded Power of String JSON base64 Basically, you can put pretty much anything, but don't go too far… These are Strings as well
26. URLSession Reloaded Extracting JSON from taskDescription VOD
    VSM4FTTJPO @
    TFTTJPO
    63-4FTTJPO
    EPXOMPBE5BTL
    63-4FTTJPO%PXOMPBE5BTL
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    EJE'JOJTI%PXOMPBEJOH5P
    MPDBUJPO
    63-
    \
    
    
    
    
    JG
    MFU
    EFTDSJQUJPO
    
    EPXOMPBE5BTLUBTL%FTDSJQUJPO
    
    
    
    
    
    
    
    MFU
    EBUB
    
    EFTDSJQUJPOEBUB VTJOH
    VUG
    
    
    
    
    
    
    
    MFU
    KTPO
    
    USZ
    +40/4FSJBMJ[BUJPOKTPO0CKFDU XJUI
    EBUB
    PQUJPOT
    <> 

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    BT
    /4%JDUJPOBSZ
    \
    
    
    
    
    
    
    
    
    JG
    
    MFU
    UZQF
    
    KTPO<UZQF>
    BT
    4USJOH
    \
    
    
    
    
    
    
    
    
    
    
    
    
    TXJUDI
    UZQF
    \
    
    
    
    
    
    
    
    
    
    
    
    
    DBTF
    BSUJDMF
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    JG
    MFU
    BSUJDMF*%
    
    KTPO<BJE>
    BT
    4USJOH
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    MFU
    QBUI5P4BWF
    
    KTPO<QBUI>
    BT
    4USJOH
    \
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    MFU
    QBUI
    
    QBUI5P4BWF
    BT
    /44USJOH FYQBOEJOH5JMEF*O1BUI
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    NPWF
    GJMF
    GSPN
    MPDBUJPO
    UP
    UIJT
    QBUI
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ^
    
    
    
    
    
    
    
    
    
    
    
    
    DBTF
    BET
    
    ǘ
    
    
    
    
    
    
    
    
    
    
    
    
    DBTF
    JNBHF
    
    ǘ
    
    
    
    
    
    
    
    
    
    
    
    
    EFGBVMU
    CSFBL
    
    
    
    
    
    
    
    
    
    
    
    
    ^
    
    
    
    
    
    
    
    
    ^
    
    
    
    
    ^
    ^
27. URLSession Reloaded UIApplicationDelegate DMBTT
    "QQ%FMFHBUF
    6*3FTQPOEFS
    6*"QQMJDBUJPO%FMFHBUF
    \
    

    
    GVOD
    BQQMJDBUJPO @
    BQQMJDBUJPO
    6*"QQMJDBUJPO 

    
    
    
    IBOEMF&WFOUT'PS#BDLHSPVOE63-4FTTJPO
    JEFOUJGJFS
    4USJOH 

    
    
    
    DPNQMFUJPO)BOEMFS
    !FTDBQJOH
    
    
    7PJE
    \
    

    
    
    
    
    $BMMFE
    XIFO
    UIF
    BQQMJDBUJP
    
    
    
    
    DPNQMFUJPO)BOEMFS
    
    
    ^
    
 ^
28. URLSession Reloaded ZDownloader https://gist.github.com/codelynx/806913e8b4122d5ea0997fad386b97a0
29. URLSession Reloaded ZDownloader architecture ZDownloader ZDownloadable ZDownloaderDelegate request URLSession request delegate find find
30. URLSession Reloaded ZDownloader • Should be setup at launch time • Schedule downloading • A ZDownloader for a session • delegate of URLSession • ask ZDownloaderDelegate to fetch / construct ZDownloadable • decode JSON and pass downloaded binary to ZDownloadable
31. URLSession Reloaded ZDownloadDelegate • Knows how to find or create ZDownloadable from JSON
32. URLSession Reloaded ZDownloadable • Represent a downloadable object • NSDictionary to represent that downloadable object uniquely • Will get called when download is completed or error
33. URLSession Reloaded Sample Project Image Downloader
34. URLSession Reloaded ZDownloader architecture ZDownloader ZDownloadable ZDownloaderDelegate request URLSession request delegate find find
35. URLSession Reloaded ZDownloader architecture ZDownloader ZDownloadable ZDownloaderDelegate request URLSession request delegate find find
36. URLSession Reloaded Sample Project
37. URLSession Reloaded ZDownloaderSample
38. URLSession Reloaded ZDownloaderSample • Pick 256 images from 5000 URLs randomly • Download images in background • Show downloaded images in Collection View • Tap "reload" to re-pick 256 images and download
39. URLSession Reloaded Thanks