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NSURLConnectionDataDelegate方法中有：
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
//This method is called when the server has determined that it
//has enough information to create the NSURLResponse.
//It can be called multiple times, for example in the case of a
//redirect, so each time we reset the data.
//receivedData is an instance variable declared elsewhere.
NSLog(@"要下载文件大小为 %lld",response.expectedContentLength);
[self.receivedData setLength:0];
}
//在此方法中可以更新进度条 -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{ //PRovide an indication of the connection's progress to the user. //progressView.progress = [self.receivedData length] / totalSize [self.receivedData appendData:data];}
复制代码
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