原因如下:
There's no problem with your implementation. All those warnings mean is the apps which each URL scheme refer to are not installed on the device.
If you're testing on the simulator, you'll get those errors all the time. But, if you test on a device, you can verify the errors will be gone if you have the corresponding apps installed.
For example, if you have the Youtube app on your device, you won't see the line:
2015-09-07 15:44:14.071 Contacts++[82438:4826277] LaunchServices: ERROR: There is no registered handler for URL scheme com-google-gidconsent-youtube