一个很好的IOS学习网站：

遇到NSURLSession后台上传文件的问题，得到这个地方的指点：

 后解决，非常感谢

具体的实现：

AppDelegate.m中，加入后台处理函数

- (void)application:(UIApplication *)application handleEventsForBackgroundURLSession:(NSString *)identifier completionHandler:(void (^)())completionHandler{        self.backgroundTransferCompletionHandler = completionHandler;    }

ViewController.h加入delegate

@interface ViewController : UIViewController 
     

 

下面是具体的实现，这里任务需要，我们是串行地上传，其实并行上传更方便

////  ViewController.m//  BackgroundTransfer////  Created by feixiang on 16/6/14.//  Copyright (c) 2014 ___FULLUSERNAME___. All rights reserved.//#import "ViewController.h"#import "FileUploadInfo.h"#import "AppDelegate.h"// Define some constants regarding the tag values of the prototype cell's subviews.#define CellLabelTagValue               10#define CellStartPauseButtonTagValue    20#define CellStopButtonTagValue          30#define CellProgressBarTagValue         40#define CellLabelReadyTagValue          50@interface ViewController ()@property (nonatomic, strong) NSURLSession *session;@property (nonatomic, strong) NSURLSessionUploadTask *task;@property (nonatomic) BOOL isDoing;@property (nonatomic, strong) NSMutableArray *arrUploadList;// 文件存放地址@property (nonatomic, strong) NSString *documentsDirectory;@property (nonatomic, strong) NSString *boundary;@property (nonatomic, strong) NSString *fileParam;@property (nonatomic, strong) NSURL *uploadURL;@property (nonatomic, strong) NSNumber *currentIndex;@end@implementation ViewController- (void)initUploadList{    self.arrUploadList = [[NSMutableArray alloc] init];    NSArray *fileList = [self getFiles:self.documentsDirectory];        for(NSString* file in fileList)    {        NSString* filePath = [self getFilePath:file];        [self.arrUploadList addObject:[[FileUploadInfo alloc] initWithFileTitle:file andFilePath:filePath]];    }    }    // 继承tableview的函数- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{    return 1 ;}- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{    return self.arrUploadList.count ;}- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{    return 60.0;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"idCell"];    if( cell == nil ){        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"idCell" ];    }    FileUploadInfo *uploader = [self.arrUploadList objectAtIndex:indexPath.row];    UILabel *title = (UILabel *)[cell viewWithTag:CellLabelTagValue];    // 设置属性    title.text = uploader.fileTitle;    return cell ;}- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.isDoing = NO ;        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    self.documentsDirectory = [paths objectAtIndex:0];    self.tblFiles.delegate = self ;    self.tblFiles.dataSource = self ;        [self initUploadList];    [self BgUploadInitSession];    }// -------------
     
      后台传输函数----------- (void)BgUploadInitSession{    // 这里加入后台下载功能    // https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/URLLoadingSystem/Articles/UsingNSURLSession.html    NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfiguration:@"com.yuanfang"];    // 后台下载用 backgroundSessionConfiguration，先用默认的设置    //NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];        //sessionConfiguration.HTTPMaximumConnectionsPerHost = 5;    self.session = [NSURLSession sessionWithConfiguration:sessionConfiguration                                                 delegate:self                                            delegateQueue:nil];        // 初始化上传地址    self.boundary = @"----------V2ymHFg03ehbqgZCaKO6jy" ;    self.uploadURL = [NSURL URLWithString:@"http://xxxx/Upload/"];}- (NSMutableURLRequest *)BgUploadSetHeader{    NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:self.uploadURL];    [request setHTTPMethod:@"POST"];    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", self.boundary];    [request setValue:contentType forHTTPHeaderField: @"Content-Type"];        return request ;}- (NSURL *)BgUploadSetUrl:(NSString *)uploadFilePath{    NSData *body = [self BgUploadPrepareData:uploadFilePath] ;    NSString* uploadFile_tmp = [NSString stringWithFormat:@"%@_tmp" ,uploadFilePath ];    [body writeToFile:uploadFile_tmp atomically:true];        // 上传完成后需要将临时文件删除    NSString *filePath = [[NSString stringWithFormat:@"file://%@", uploadFile_tmp] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    NSURL *fileUrl =  [NSURL URLWithString:filePath];        return fileUrl;}// 这里删除文件有点问题- (void)BgUploadRemoveTmpFile:(NSString *)tmpFilepath{    tmpFilepath = [NSString stringWithFormat:@"%@_tmp",tmpFilepath];    tmpFilepath = [[NSString stringWithFormat:@"file://%@", tmpFilepath] stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];    NSFileManager *defaultManager;    defaultManager = [NSFileManager defaultManager];    NSError *error ;    BOOL ret = [defaultManager removeItemAtPath:tmpFilepath error:&error];    if( ret == NO )        NSLog(@"\nerror:%@",error);}- (NSData*) BgUploadPrepareData:(NSString *)filePath{    NSFileManager *fileManager = [NSFileManager defaultManager];    BOOL fileExists = [fileManager fileExistsAtPath:filePath];        NSMutableData *body = [NSMutableData data];    if( fileExists == YES ){        NSString *fileName = [filePath lastPathComponent];                NSData *dataOfFile = [[NSData alloc] initWithContentsOfFile:filePath];                // 组装POST格式        if (dataOfFile) {            [body appendData:[[NSString stringWithFormat:@"--%@\r\n", self.boundary] dataUsingEncoding:NSUTF8StringEncoding]];            [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"file\"; filename=\"%@\"\r\n", fileName] dataUsingEncoding:NSUTF8StringEncoding]];            [body appendData:[@"Content-Type: application/zip\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];            [body appendData:dataOfFile];            [body appendData:[[NSString stringWithFormat:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];        }        [body appendData:[[NSString stringWithFormat:@"--%@--\r\n", self.boundary] dataUsingEncoding:NSUTF8StringEncoding]];    }    return body;}- (void)BgUploadCommon:(NSString *)uploadFilePath{    // 由于fromFile会覆盖原来的http请求的body内容。可以先构造一个request，然后将body信息存到文件里面，提供给task调用    // 1 ， 构造 HTTP Request POST HEADER    NSMutableURLRequest *request = [self BgUploadSetHeader];    // 2 , 将文件和保存文件form-data信息一起保存到磁盘临时文件中    NSURL *fileUrl = [self BgUploadSetUrl:uploadFilePath];    // 3，使用task的fromFile上传函数    self.task = [self.session uploadTaskWithRequest:request fromFile:fileUrl];    // 启动后台任务，下面回调函数接收消息    [self.task resume];}// ----------end 后台传输--------//----------------各个按钮事件- (IBAction)startAll:(id)sender{    if( self.isDoing == NO ){        [self.buttonStart setTitle:@"STOP" forState:UIControlStateHighlighted];        self.isDoing = YES;    }else{        [self.buttonStart setTitle:@"START" forState:UIControlStateHighlighted];        self.isDoing = NO;    }    FileUploadInfo *uploader = [self.arrUploadList objectAtIndex:0];    [self BgUploadCommon:uploader.filePath];}- (IBAction)stopUpload:(id)sender{    if( self.task.state == NSURLSessionTaskStateRunning ){         [self.task suspend];    }}- (IBAction)resumeUpload:(id)sender{    if( self.task.state == NSURLSessionTaskStateRunning ){        [self.task resume];    }}- (IBAction)cancelUpload:(id)sender{    if( self.task.state == NSURLSessionTaskStateRunning ){        [self.task cancel];    }}//----------------NSURLSession回调函数-------------------------// 上传进度中- (void)URLSession:(NSURLSession *)session              task:(NSURLSessionTask *)task   didSendBodyData:(int64_t)bytesSent    totalBytesSent:(int64_t)totalBytesSenttotalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend{    NSLog(@"\n%f / %f", (double)totalBytesSent,          (double)totalBytesExpectedToSend);        // 更新界面    //int index = [self getIndexWithTaskIdentifier:task.taskIdentifier];    int index = [self.currentIndex intValue];    FileUploadInfo *uploader = [self.arrUploadList objectAtIndex:index];        [[NSOperationQueue mainQueue] addOperationWithBlock:^{        uploader.progress = (double)totalBytesSent / (double)totalBytesExpectedToSend;                UITableViewCell *cell = [self.tblFiles cellForRowAtIndexPath:[NSIndexPath indexPathForRow:index inSection:0]];        UIProgressView *progressView = (UIProgressView *)[cell viewWithTag:CellProgressBarTagValue];        progressView.progress = uploader.progress;    }];}// 上传完成- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{    // 这里继续做下一个任务    [self BgUploadBeginNextTask];}- (void)BgUploadBeginNextTask{    //int index = [self getIndexWithTaskIdentifier:task.taskIdentifier] + 1 ;    self.currentIndex = @([self.currentIndex intValue] + 1 );    int index = [self.currentIndex intValue];    FileUploadInfo *uploader = [self.arrUploadList objectAtIndex:index];        NSLog(@"\n第 %@ 个任务 %@ 完成 ",self.currentIndex, uploader.filePath);        UILocalNotification *localNotification = [[UILocalNotification alloc] init];    localNotification.alertBody = [NSString stringWithFormat:@"%@ have been uploaded!",uploader.filePath];    [[UIApplication sharedApplication] presentLocalNotificationNow:localNotification];            //先删除临时文件    [self BgUploadRemoveTmpFile:uploader.filePath];    if( index < [self.arrUploadList count] ){        [self BgUploadCommon:uploader.filePath];    }}// 后台传输完成，处理URLSession完成事件-(void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session{    AppDelegate *appDelegate = [UIApplication sharedApplication].delegate;        // Check if all download tasks have been finished.    [self.session getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {        if ([uploadTasks count] == 0) {            if (appDelegate.backgroundTransferCompletionHandler != nil) {                // Copy locally the completion handler.                void(^completionHandler)() = appDelegate.backgroundTransferCompletionHandler;                                // Make nil the backgroundTransferCompletionHandler.                appDelegate.backgroundTransferCompletionHandler = nil;                                [[NSOperationQueue mainQueue] addOperationWithBlock:^{                    completionHandler();                                        // 这里继续做下一个任务                    [self BgUploadBeginNextTask];                }];            }        }                    }];}-(int)getIndexWithTaskIdentifier:(unsigned long)taskIdentifier{    int index = 0;    for (int i=0; i<[self.arrUploadList count]; i++) {        FileUploadInfo *uploader = [self.arrUploadList objectAtIndex:i];        if (uploader.taskIdentifier == taskIdentifier) {            index = i;            break;        }    }        return index;}//----------------END NSURLSession回调函数-----------------------// 获取目录下的所有文件-(NSArray*)getFiles:(NSString *)dir{    NSFileManager* fm = [NSFileManager defaultManager];    NSArray* array = [fm contentsOfDirectoryAtPath:dir error:nil ];    NSMutableArray* fileList = [[NSMutableArray alloc]init];        BOOL isDir = NO ;    for(NSString* file in array)    {        [fm fileExistsAtPath:file isDirectory:&isDir];        if( !isDir && ![file isEqualToString:@".DS_Store"])            [fileList addObject:file];    }    return fileList ;}- (NSString*)getFilePath:(NSString *)filename{    NSString *uploadFilePath = [self.documentsDirectory stringByAppendingPathComponent:filename];    return uploadFilePath;}- (void)didReceiveMemoryWarning{    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end
     

 

 http://numbbbbb.gitbooks.io/-the-swift-programming-language-/