Because it is encountering a debug assertion in libc++, Xcode stalls. To avoid this: First, turn off exception breakpoints: You can delete any exception breakpoint by opening the Breakpoints Navigator (⌘8). 2. Turn off LIBCPP_DEBUG Claims: a. Select Scheme > Product > Edit Scheme (⌘⇧,). a. Add by selecting Run > Arguments: _LIBCPP_DEBUG = 0.
Disregard LLDB assertions: a. Type breakpoint set -s libc++ -n __cxa_throw -G 0 into the Debug Console (⌘⇧C). b. manage the SIGTRAP procedure --stop false --notify false --pass true
As a final resort, run in Release Mode: a. Change the Run configuration to Release in Edit Scheme.
By doing this, _LIBCPP_ASSERT_SEMANTIC_REQUIREMENT will no longer cause the debugger to pause.