[iOS]获取网络文件大小

今天记录一下根据已知的图片、音频或视频等网络文件的地址，来获取文件的大小

- (void)getUrlFileLength:(NSString *)url
{
    url = [[NSString alloc] initWithData:[[url stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]] dataUsingEncoding:NSUTF8StringEncoding] encoding:NSUTF8StringEncoding];
    NSMutableURLRequest *mURLRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]];
    [mURLRequest setHTTPMethod:@"HEAD"];
    mURLRequest.timeoutInterval = 5.0;
    
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:mURLRequest];
    [dataTask resume];
}

-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler
{
    NSDictionary *dict = [(NSHTTPURLResponse *)response allHeaderFields];
    NSNumber *length = [dict objectForKey:@"Content-Length"];
    [dataTask cancel];
    NSLog(@"%@", length);
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didCompleteWithError:(nullable NSError *)error {
    NSLog(@"%@", error);
}