iOS - 小文件下载篇(边下载边写入文件)

#define MSFileWithPath(path) [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:path]
 


- (void)viewDidLoad {
    [super viewDidLoad];
    
    NSString *urlString = @"http://120.25.226.186:32812/resources/videos/minion_15.mp4";
    urlString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSURL *url = [NSURL URLWithString:urlString];
    
    [NSURLConnection connectionWithRequest:[NSURLRequest requestWithURL:url] delegate:self];
}

#pragma mark - <NSURLConnectionDataDelegate>
// 接收到响应的时候：创建一个空的文件
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response {
    // 获得文件的总长度
    self.contentLength = [response.allHeaderFields[@"Content-Length"] integerValue];
    
    // 创建一个空的文件
    [[NSFileManager defaultManager] createFileAtPath:MSFileWithPath(@"minion_15.mp4") contents:nil attributes:nil];
    
    // 创建文件句柄
    self.handle = [NSFileHandle fileHandleForWritingAtPath:MSFileWithPath(@"minion_15.mp4")];
    
}
 
// 接收到具体数据：马上把数据写入一开始创建好的文件
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    // 指定数据的写入位置 -- 文件内容的最后面
    [self.handle seekToEndOfFile];
    
    // 写入数据
    [self.handle writeData:data];
    
    // 拼接总长度
    self.currentLength += data.length;
    
    // 进度
    self.progressView.progress = 1.0 * self.currentLength / self.contentLength;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    // 关闭handle
    [self.handle closeFile];
    self.handle = nil;
    
    // 清空长度
    self.currentLength = 0;    
}