详解Swift 利用Opration和OprationQueue来下载网络图片

详解swift 利用opration和oprationqueue来下载网络图片

1. 基于opration封装的获取网络数据组件

import foundation 
import uikit 
 
public typealias opreationclosure = ((_ data:data? , _ error: error?) -> void) 
 
class ljopreationmanager: operation { 
   
  /** 
   * 下载用的url 
   */ 
  public var imageurl : string? 
   
  /** 
   * 定义闭包属性,可选类型 
   */ 
  public var ljcallbackclosure : opreationclosure? 
   
  func initwitparamter(_ url: string, _ callback: @escaping opreationclosure) -> ljopreationmanager { 
     
    if url != "" 
    { 
      self.imageurl = url 
      self.ljcallbackclosure = callback 
    } 
    return self 
  } 
   
  //mark: -- start 
  override func start() { 
     
    print("start ljmanager method") 
    self.startrequest() 
  } 
   
  func startrequest() 
  { 
    //1、创建url下载地址 
    let url:url! = url(string:self.imageurl!); 
     
    //2、创建request对象 
    var urlrequest:urlrequest = urlrequest(url:url); 
    urlrequest.httpmethod = "get" 
    urlrequest.httpshouldusepipelining = true; 
     
    //不需要缓存 
    //urlrequest.cachepolicy = .reloadignoringlocalcachedata 
     
    //3、创建会话 
    let config = urlsessionconfiguration.default 
    let session = urlsession(configuration: config, delegate:self, delegatequeue: .main) 
     
    //4、下载任务 
    //2>-- -- urlsessiondatadelegate 模式 
    let loaddatatask = session.datatask(with: urlrequest) 
     
    //5、启动任务 
    loaddatatask.resume() 
  } 
   
  //初始化一个data，用来存储下载下来的数据 
  private var _responsedata: nsmutabledata! 
  var responsedata: nsmutabledata!{ 
    get{ 
      if _responsedata == nil { 
        _responsedata = nsmutabledata() 
      } 
      return _responsedata 
    } 
    set{ 
      self._responsedata = newvalue 
    } 
  } 
} 
 
// mark - urlsessiondatadelegate 模式获取数据 
extension ljopreationmanager:urlsessiondatadelegate 
{ 
  @available(ios 7.0, *) 
  func urlsession(_ session: urlsession, datatask: urlsessiondatatask, didreceive response: urlresponse, completionhandler: @escaping (urlsession.responsedisposition) -> swift.void) 
  { 
    //允许继续加载数据 
    completionhandler(.allow) 
  } 
   
  @available(ios 7.0, *) 
  func urlsession(_ session: urlsession, datatask: urlsessiondatatask, didreceive data: data) 
  { 
    //每次获取的data在此拼装 
    //print("data......\(data)") 
    self.responsedata.append(data) 
     
    let currentbytes :float = float(self.responsedata.length) 
    let alltotalbytes :float = float((datatask.response?.expectedcontentlength)!) 
     
    let provalu :float = float(currentbytes/alltotalbytes) 
    print("urlsessiondatadelegate----下载进度:------\(provalu*100)%"); 
  } 
   
  func urlsession(_ session: urlsession, task: urlsessiontask, didcompletewitherror error: error?) 
  { 
    if ljcallbackclosure != nil ,let data = self.responsedata{ 
       
      weak var weakself : ljopreationmanager? = self 
      dispatchqueue.main.async 
        { 
          print("urlsessiondatadelegate----数据下载完毕") 
          //将接收的数据结果回调到前台，用于进度展示 
          weakself?.ljcallbackclosure!(data as data ,nil) 
      } 
    } 
  } 
} 

2. 基于oprationqueue封装的网络数据管理组件

import foundation 
 
class ljwebimagemanager: nsobject { 
   
  /// shared manager used . 
  public static let shared = ljwebimagemanager() 
  public var ljquee = operationqueue() 
   
  override init() { 
    if #available(ios 8.0, *) { 
      self.ljquee.qualityofservice = .background 
    } else { 
    } 
  } 
   
  public func requestbyurl(_ url: string,_ callback: @escaping opreationclosure) -> ljopreationmanager { 
    let operation = ljopreationmanager().initwitparamter(url, callback) 
    ljquee.addoperation(operation) 
     
    return operation 
  } 
} 

3. 此处下载一张图片

func setcelldata(_ labelnamestr:string, imageurlstr:string) 
{ 
  titlelabel.text = labelnamestr as string 
  /* session 的delegate模式下载图片或者数据*/ 
  _ = ljwebimagemanager.shared.requestbyurl(imageurlstr, { (data, error) in 
     
    if error == nil, data != nil { 
      let newimage = uiimage(data: data! as data) 
       
      dispatchqueue.main.async{ 
        let titleimage = uiimageview(frame: cgrect(x: 0, y: 5, width: 40, height: 40)) 
        titleimage.image = newimage 
        self.contentview.addsubview(titleimage) 
      } 
    } 
    else 
    { 
      print(error ?? "") 
    } 
  }) 
} 

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