ArcGIS Runtime for iOS AGSFeatureLayer加载要素图层无法正常显示，但是在浏览器用JavaScript API又能正常显示，请问我的代码有什么问题

NSURL *featureLayerURL = [NSURL URLWithString:@"http://58.42.237.172:9994/arcg ... ot%3B];
_featureLayer = [[AGSFeatureLayer alloc]initWithURL:featureLayerURL mode:AGSFeatureLayerModeOnDemand];
_featureLayer.outFields =@[@"*"];
[self.mapView addMapLayer:_featureLayer withName:@"CloudData"];