应用程序不使用 NSURLConnection 下载文件

Question

我有一个应用程序，它循环遍历 URL 数组并下载该数组中的所有文件（10 个小 txt 文件和 1 个大图像文件）。之前我的应用程序可以下载文件，但由于大图像的问题，我不得不将 NSURLConnection 子类化，我认为我还没有完全正确，因为现在没有文件被下载。

为数组 getFiles 的每一项传递一个 URL 并运行：

-(void)getFile:(NSString*)url tag:(NSString*)tag {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];
    FileURLConnection *connection = [[FileURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES tag:tag];
    if (connection) {
        [receivedData setObject:[NSMutableData data] forKey:connection.tag];
    }
}

这里是 NSURLConnection 代表：

-(NSMutableData*)dataForConnection:(FileURLConnection*)connection {
    NSMutableData *data = [receivedData objectForKey:connection.tag];
    return data;
}
- (void)connection:(FileURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSUserDomainMask, YES) objectAtIndex:0]stringByAppendingPathComponent:fileName];
    NSMutableData *dataForConnection = [self dataForConnection:(FileURLConnection*)connection];
    [dataForConnection setLength:0];
}
- (void)connection:(FileURLConnection *)connection didReceiveData:(NSData *)data {
    NSMutableData *dataForConnection = [self dataForConnection:(FileURLConnection*)connection];
    [dataForConnection appendData:data];
}
- (NSCachedURLResponse *)connection:(FileURLConnection *)connection
              willCacheResponse:(NSCachedURLResponse*)cachedResponse {
    return nil;
}
- (void)connectionDidFinishLoading:(FileURLConnection *)connection {
    NSLog(@"connectionDidFinishLoading run");
    NSMutableData *dataForConnection = [self dataForConnection:(FileURLConnection *)connection];
    NSString *fileName = connection.tag;
    NSString *filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]stringByAppendingPathComponent:fileName];
    [[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
    file = [NSFileHandle fileHandleForUpdatingAtPath:filePath];
    [file seekToEndOfFile];
    [file writeData:dataForConnection];
    [file closeFile];
}

编辑：如果我在 getFile 中 NSLog 接收到的数据（NSDictionary），它会更新“标签”对象，但没有数据与之相关：

"accomodation.txt" = <>;
"future-congress-dates.txt" = <>;
"general-file.txt" = <>;
...

我还尝试为每个委托对 dataForConnection (NSMutableData) 进行 NSLog 记录，但没有打印任何内容：

NSLog(@"dataForConnection %@", dataForConnection);

Answer 1

好吧，我投降了。 有完整代码：

文件URL连接：

@interface FileURLConnection: NSURLConnection

@property (nonatomic, strong) NSFileHandle *file;

@end

getFile函数：

-(void)getFile {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:fullURL]];
    FileURLConnection *conn = [[FileURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];
}
- (void)connection:(FileURLConnection*)connection didReceiveResponse:(NSURLResponse *)response {
    NSString *fileName = [[response URL] lastPathComponent];
    NSString *filePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]stringByAppendingPathComponent:fileName];
    [[NSFileManager defaultManager] createFileAtPath:filePath contents:nil attributes:nil];
    connection.file = [NSFileHandle fileHandleForUpdatingAtPath:filePath];
}
- (void)connection:(FileURLConnection *)connection didReceiveData:(NSData *)data {
    [connection.file writeData:data]; 
}
- (NSCachedURLResponse *)connection:(FileURLConnection *)connection
              willCacheResponse:(NSCachedURLResponse*)cachedResponse {
    return nil;
}
- (void)connectionDidFinishLoading:(FileURLConnection *)connection {
    NSLog(@"Connection is %@", connection);
    [connection.file closeFile];
}
- (void)connection:(FileURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"error - %@", error);
}

原问题：App crashing when downloading a large file - NSFileHandle seekToEndOfFile