You can use the method behavior +URLWithString:relativeToURL:to override baseURL.
Matt mentioned this in Docs
HTTP- URL- baseURL, NSURL + URLWithString: relativeToURL:, . baseURL , NSURL, NSURL + URLWithString:.
baseURL :
NSURL *baseURL = [NSURL URLWithString:@"http://example.com/v1/"];
[NSURL URLWithString:@"foo" relativeToURL:baseURL];
[NSURL URLWithString:@"foo?bar=baz" relativeToURL:baseURL];
[NSURL URLWithString:@"/foo" relativeToURL:baseURL];
[NSURL URLWithString:@"foo/" relativeToURL:baseURL];
[NSURL URLWithString:@"/foo/" relativeToURL:baseURL];
[NSURL URLWithString:@"http://example2.com/" relativeToURL:baseURL];
, baseURL , URL URLString GET:parameters:success:failure: URL-.
[manager GET:@"http://otherBaseURL.com/url/path" parameters:nil success:... failure:...]