AF请求报Error Domain=NSURLErrorDoma

报错原因是请求的url 不需要验证域名和请求类型格式

所以修改AFNetworking 请求方式
NSString *url = @"https:xxxxxxxx.txt";
url是txt格式 ，添加text/plain 解决
session.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"text/plain", nil];

以下是正确请求方式

 NSString *url = @"https:xxxxxxxx.txt"; 
AFHTTPSessionManager *session = [AFHTTPSessionManager manager];
    // 不用验证域名 没写的话 Error Domain=NSURLErrorDomain Code=-999
    AFSecurityPolicy *secur = [AFSecurityPolicy policyWithPinningMode:AFSSLPinningModeNone];
    [secur setValidatesDomainName:NO];
    session.securityPolicy = secur;

    session.responseSerializer.acceptableContentTypes = [NSSet setWithObjects:@"application/json", @"text/json", @"text/javascript", @"text/html",@"text/plain", nil];
    [session.securityPolicy setAllowInvalidCertificates:YES];
    
    [session GET:url parameters:nil progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {

        NSString *urlString = responseObject[@"iosURL"];

    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {

    } ];