iOS 支援多任務、斷點下載(圖片、音頻、視頻) (Demo 一)

標籤：ios

具體使用請到我的GitHub
代碼: https://github.com/HHuiHao/HSDownloadManager

功能示範：

—————–代碼實現—————–

開啟任務下載資源方法，新開線程並執行下載任務

- (void)download:(NSString *)url progress:(void (^)(NSInteger, NSInteger, CGFloat))progressBlock state:(void (^)(DownloadState))stateBlock{    // 驗證    if (!url) return;    if ([self isCompletion:url]) {        stateBlock(DownloadStateCompleted);        NSLog(@"----該資源已下載完成");        return;    }    // 暫停    if ([self.tasks valueForKey:HSFileName(url)]) {        [self handle:url];        return;    }    // 建立緩衝目錄檔案    [self createCacheDirectory];   NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];    // 建立流    NSOutputStream *stream = [NSOutputStream outputStreamToFileAtPath:HSFileFullpath(url) append:YES];    // 建立請求    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];    // 佈建要求頭    NSString *range = [NSString stringWithFormat:@"bytes=%zd-", HSDownloadLength(url)];    [request setValue:range forHTTPHeaderField:@"Range"];    // 建立一個Data任務    NSURLSessionDataTask *task = [session dataTaskWithRequest:request];    NSUInteger taskIdentifier = arc4random() % ((arc4random() % 10000 + arc4random() % 10000));    [task setValue:@(taskIdentifier) forKeyPath:@"taskIdentifier"];    // 儲存任務    [self.tasks setValue:task forKey:HSFileName(url)];    HSSessionModel *sessionModel = [[HSSessionModel alloc] init];    sessionModel.url = url;    sessionModel.progressBlock = progressBlock;    sessionModel.stateBlock = stateBlock;    sessionModel.stream = stream;    [self.sessionModels setValue:sessionModel forKey:@(task.taskIdentifier).stringValue];    [self start:url];}

分解方法：

• 驗證資訊

    if (!url) return;    if ([self isCompletion:url]) {        stateBlock(DownloadStateCompleted);        NSLog(@"----該資源已下載完成");        return;    }    // 暫停    if ([self.tasks valueForKey:HSFileName(url)]) {        [self handle:url];        return;    }

• 網路請求實現：NSURLSession

NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];

• 接收data流：NSOutputStream

NSOutputStream *stream = [NSOutputStream outputStreamToFileAtPath:HSFileFullpath(url) append:YES];

• 建立請求並佈建要求頭資訊

// 建立請求NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];// 佈建要求頭NSString *range = [NSString stringWithFormat:@"bytes=%zd-", HSDownloadLength(url)];[request setValue:range forHTTPHeaderField:@"Range"];

• 並建立一個data任務：NSURLSessionDataTask

NSURLSessionDataTask *task = [session dataTaskWithRequest:request];NSUInteger taskIdentifier = arc4random() % ((arc4random() % 10000 + arc4random() % 10000));[task setValue:@(taskIdentifier) forKeyPath:@"taskIdentifier"];

• 儲存每個NSURLSessionDataTask任務：self.tasks

[self.tasks setValue:task forKey:HSFileName(url)];

• 相關請求資訊回調方法封裝到model: HSSessionModel

```objcHSSessionModel *sessionModel = [[HSSessionModel alloc] init];sessionModel.url = url;sessionModel.progressBlock = progressBlock;sessionModel.stateBlock = stateBlock;sessionModel.stream = stream;[self.sessionModels setValue:sessionModel forKey:@(task.taskIdentifier).stringValue];[self start:url];

接收處理資料 NSURLSessionDataDelegate接收資料

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSHTTPURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler{    HSSessionModel *sessionModel = [self getSessionModel:dataTask.taskIdentifier];    // 開啟流    [sessionModel.stream open];    // 獲得伺服器這次請求 返回資料的總長度    NSInteger totalLength = [response.allHeaderFields[@"Content-Length"] integerValue] + HSDownloadLength(sessionModel.url);    sessionModel.totalLength = totalLength;    // 儲存總長度    NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithContentsOfFile:HSTotalLengthFullpath];    if (dict == nil) dict = [NSMutableDictionary dictionary];    dict[HSFileName(sessionModel.url)] = @(totalLength);    [dict writeToFile:HSTotalLengthFullpath atomically:YES];    // 接收這個請求，允許接收伺服器的資料    completionHandler(NSURLSessionResponseAllow);}

接收到伺服器返回的資料

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data{    // 擷取模型    HSSessionModel *sessionModel = [self getSessionModel:dataTask.taskIdentifier];    // 寫入資料    [sessionModel.stream write:data.bytes maxLength:data.length];    // 下載進度    NSUInteger receivedSize = HSDownloadLength(sessionModel.url);    NSUInteger expectedSize = sessionModel.totalLength;    CGFloat progress = 1.0 * receivedSize / expectedSize;    // block回調    sessionModel.progressBlock(receivedSize, expectedSize, progress);}

請求完畢（成功或失敗）

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{    HSSessionModel *sessionModel = [self getSessionModel:task.taskIdentifier];    if (!sessionModel) return;    if ([self isCompletion:sessionModel.url]) {        // 下載完成        sessionModel.stateBlock(DownloadStateCompleted);    } else if (error){        // 下載失敗        sessionModel.stateBlock(DownloadStateFailed);    }    // 關閉流    [sessionModel.stream close];    sessionModel.stream = nil;    // 清除任務    [self.tasks removeObjectForKey:HSFileName(sessionModel.url)];    [self.sessionModels removeObjectForKey:@(task.taskIdentifier).stringValue];}

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iOS 支援多任務、斷點下載(圖片、音頻、視頻) (Demo 一)