从网络上下载大文件(视频)

- (IBAction)getbigfile:(UIButton *)sender {
    NSString *str = @"http://b.hiphotos.baidu.com/video/pic/item/e850352ac65c1038698cd94eb7119313b17e894f.jpg";
    NSURL *url = [NSURL URLWithString:str];

    NSURLRequest * request = [[NSURLRequest alloc]initWithURL:url];

    NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self startImmediately:YES];
    [conn start];

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
        self.receivedData = [[NSMutableData alloc]init];

}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    [self.receivedData appendData:data];
    NSLog(@"接受到服务器端来的数据%d",data.length);
 NSString *Data =[[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];

    NSLog(@"%@",Data);
}

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

    NSLog(@"222");

    NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/a.mp4"];
    NSLog(@"string = %@",path);
    [self.receivedData writeToFile:path atomically:YES];
}