iOS10 symbol(s) not found for architecture arm64

Question

Undefined symbols for architecture arm64:
"_OBJC_CLASS_$_UNUserNotificationCenter", referenced from:

  objc-class-ref in AppDelegate.o

ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

iOS10 之前没有错误 这是之前写的 但是现在报错