逆向时,lldb中breakpoint对函数下断点,breakpoint set -F “-[XXXClass XXXFunction:]”,下不了?

请教一下:
在逆向时,相对某个函数下个断点,例如,对-[NSArray objectAtIndex:]下断点是是正常的:
(lldb) breakpoint set -F “-[NSArray objectAtIndex:]”
Breakpoint 13: where = CoreFoundation`-[NSArray objectAtIndex:], address = 0x00000001833fa744

可是对APP中自己声明的类和方法下断点时,始终下不了:
(lldb) breakpoint set -F “-[XXXClass XXXFunction:]”
Breakpoint 4: no locations (pending).
WARNING: Unable to resolve breakpoint to any actual locations.

请问这是什么原因???