【求助】实战1 Notes 疑问 227页

技能讨论
1

lldb，给两个方法下断点时，

  • (void)noteContentLayer:(NoteContentLayer *)arg1 didChangeContentSize:(struct CGSize)arg2;

  • (void)noteContentLayerContentDidChange:(NoteContentLayer *)arg1 updatedTitle:(BOOL)arg2;

      (lldb) br com add 1
  	Enter your debugger command(s).  Type 'DONE' to end.
  > po $r2
  > c
  > DONE


  (lldb) br com add 2
  	Enter your debugger command(s).  Type 'DONE' to end.
  > po $r2
  > c
  > DONE

请问，这里为什么要po $r2呢？
附断点的输出：

  • thread #1: tid = 0x15b8, 0x000f5d20 MobileNotes___lldb_unnamed_function382$$MobileNotes, queue = 'com.apple.main-thread, stop reason = breakpoint 1.1 frame #0: 0x000f5d20 MobileNotes___lldb_unnamed_function382$$MobileNotes
    MobileNotes`___lldb_unnamed_function382$$MobileNotes:
    → 0xf5d20: movw r1, #48528
    0xf5d24: movt r1, #3
    0xf5d28: add r1, pc
    0xf5d2a: ldr r1, [r1]