You need to create a Watchpoint in Xcode.

This question belongs to Xcode Developer Tools , specifically the objective on using debugging techniques including breakpoints, watchpoints, and logging to resolve errors . A watchpoint monitors a variable or memory location during a debugging session, so you first need the program to stop while being debugged. That is why the correct order begins with setting a breakpoint and then running the code so execution pauses at a useful point. Apple’s debugging guidance describes debugging as something done at runtime using the debugger, and LLDB’s watchpoint documentation explains that watchpoints are part of the debugger workflow rather than something you set before the program is stopped.

Once execution is paused, you use the debug area to inspect the current variables. After locating the variable you want to monitor, you right-click the variable and select Watch to create the watchpoint. This sequence is consistent with how Xcode and LLDB expose watchpoint functionality during an active debug session. LLDB also describes watchpoints as objects you create to stop execution when a watched value changes, which only makes sense after the debugger has access to the running program state.