iOS －－下载文件的方法,大文件下载FileHandle

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1.小文件的下载方法

A.NSURL *url = [NSURLURLWithString:@"http://image2.sina.com.cn/ent/v/m/p/2005-11-11/U92P28T3D893697F329DT20051111200426.jpg"];

NSData *data = [NSDatadataWithContentsOfURL:url];

NSLog(@"%@",data);

B.[NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:url] queue:[NSOperationQueuemainQueue]completionHandler:^(NSURLResponse *_Nullable response,NSData * _Nullable data,NSError * _Nullable connectionError) {

NSLog(@"%@",data);

}];

C.[NSURLConnectionconnectionWithRequest:[NSURLRequestrequestWithURL:url]delegate:self];

2.获取文件大小的方法：两种方法：(nonnull NSURLResponse *)response －》response.expectedContentLength;

(NSHTTPURLResponse *)response －》[response.allHeaderFields[@"Content-Length"]floatValue];

-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response{

//(nonnull NSURLResponse *)response{

// _totalData = response.expectedContentLength;

_totalData = [response.allHeaderFields[@"Content-Length"]floatValue];

NSLog(@"%s,%lld",__func__,response.expectedContentLength);

}

3.NSURLConnection 需要手动写入沙盒

NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask,YES)lastObject];

NSString *file = [cachesstringByAppendingPathComponent:@"hahah.jpg"];

[self.responseDatawriteToFile:fileatomically:YES];

self.responseData =nil;

4.大文件分段下载：NSFileHandle

#define WXYFile [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject] stringByAppendingPathComponent:@"hahah.jpg"]

//创建文件句柄对象

NSFileHandle *handle = [NSFileHandlefileHandleForWritingAtPath:WXYFile];

//指定分段下载数据的写入位置

[handle seekToEndOfFile];

[handle writeData:data];

//关闭handle，下载完成后

[handle closeFile];

self.handle = nil;

self.contentLenght = [response.allHeaderField[@"Content-Length"]floatValue];

self.currentLenght += data.length;

self.progressView.progress = 1.0 * self.currentLenght / self.contentLength;

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