[iOS] AFNetworking下载及设置请求头

    __weak typeof(self) weakself = self;
    
    NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Server_generate_qrcode.png"];
//    NSString *filePath = [path stringByAppendingPathComponent:@"123"];

    AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    //manager.securityPolicy = securityPolicy;//不验证https配置，也可不写
    manager.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript",@"text/plain",@"text/html", nil];
    manager.requestSerializer = [AFHTTPRequestSerializer serializer];


    [manager.requestSerializer setValue:[GVUserDefaults standardUserDefaults].token forHTTPHeaderField:@"token"];


    NSMutableURLRequest *request = [[AFHTTPRequestSerializer serializer] requestWithMethod:@"GET" URLString:Server_generate_qrcode parameters:nil error:nil];
    [request setValue:[GVUserDefaults standardUserDefaults].token forHTTPHeaderField:@"token"];

    NSURLSessionTask *task = [_manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {
        
    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        return [NSURL fileURLWithPath:path];

    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
        
        NSLog(@"----%@",error);
        
        NSData *data = [NSData dataWithContentsOfURL:filePath];
        UIImage *image = [UIImage imageWithData:data];
        weakself.imageView.image = image;
        
        
    }];
    
    [task resume];