Your code looks like it's doing the right things but I can't tell what's going wrong based off that screenshot. Is TianDiTuWMTSLayer a subclass of AGSWMTSLayer? How are you instantiating the AGSWMTSLayer superclass from within your initializer? What are the services being accessed?
The first screenshot shows an authentication challenge from ArcGIS.com. Is that expected? Where are your two map layers hosted?
I expect there's something failing on map load, or the service isn't responding as expected. You can find out more by calling load on your AGSMap and seeing if there's an error on map load. That could help you home in on the problem.
You can also use AGSRequestConfiguration to output debug logs to the console. Get the singleton globalConfiguration and set debugLogResponses to true.
Hope that helps.
