iOS - 小文件下载篇(边下载边写入文件)

先签订 NSURLConnectionDataDelegate
协议

#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;

}

又是一个小例子, 没事可以看看～