Xcode变量看不了

问题描述：
堆栈上一层都正常，这一层监视通通挂了，任何变量看不了

(lldb) po self
error: :1:11: error: use of undeclared type '$__lldb_context'
extension $__lldb_context {
^~~~~~~~~~~~~~~

error: :18:5: error: use of unresolved identifier '$__lldb_injected_self'
$__lldb_injected_self.$__lldb_wrapped_expr_32(
^~~~~~~~~~~~~~~~~~~~~

(lldb) po viewController
error: :3:1: error: use of unresolved identifier 'viewController'
viewController
^~~~~~~~~~~~~~

Xcode Version 8.2 (8C38)