14

很多时候（不是每次）当我尝试在 lldb 上打印对象时都会出现以下错误。是否有一些构建/调试配置要更改，或者这是 lldb 内部的错误？

(lldb) po userLevel
error: warning: Stopped in an Objective-C method, but 'self' isn't available; pretending we are in a generic context
error: use of undeclared identifier 'userLevel'
error: 1 errors parsing expression

我使用 llvm 构建并且不剥离调试符号。

编辑：这是回溯：

(lldb) bt
* thread #1: tid = 0x1c03, 0x001169c5 FanCake-Beta`-[KWUserLevelController addPoints:](, _cmd=0x0029187b, points=15) + 179 at KWUserLevelController.m:53, stop reason = step over
    frame #0: 0x001169c5 FanCake-Beta`-[KWUserLevelController addPoints:](, _cmd=0x0029187b, points=15) + 179 at KWUserLevelController.m:53
    frame #1: 0x00112172 FanCake-Beta`-[KWEventRealTimeControllergameEngine:hostedGame:didSucceedIn:withScore:](self=0x0b9d7740, _cmd=0x0027a2a7, engine=0x1be5af40, game=0x1be5a850, completionTime=3.59473554800206, score=0) + 421 at KWEventRealTimeController.m:647
    frame #2: 0x0007189a FanCake-Beta`__35-[KMCatchEmGameEngine animateStep6]_block_invoke197(, finished='\x01') + 257 at KMCatchEmGameEngine.m:214
    frame #3: 0x01990df6 UIKit`-[UIViewAnimationBlockDelegate _didEndBlockAnimation:finished:context:] + 223
    frame #4: 0x01983d66 UIKit`-[UIViewAnimationState sendDelegateAnimationDidStop:finished:] + 237
    frame #5: 0x01983f04 UIKit`-[UIViewAnimationState animationDidStop:finished:] + 68
    frame #6: 0x017587d8 QuartzCore`CA::Layer::run_animation_callbacks(void*) + 284
    frame #7: 0x03634014 libdispatch.dylib`_dispatch_client_callout + 14
    frame #8: 0x036247d5 libdispatch.dylib`_dispatch_main_queue_callback_4CF + 296
    frame #9: 0x04737af5 CoreFoundation`__CFRunLoopRun + 1925
    frame #10: 0x04736f44 CoreFoundation`CFRunLoopRunSpecific + 276
    frame #11: 0x04736e1b CoreFoundation`CFRunLoopRunInMode + 123
    frame #12: 0x040367e3 GraphicsServices`GSEventRunModal + 88
    frame #13: 0x04036668 GraphicsServices`GSEventRun + 104
    frame #14: 0x01945ffc UIKit`UIApplicationMain + 1211
    frame #15: 0x000039a8 FanCake-Beta`main(argc=1, argv=0xbffff354) + 94 at main.m:13
    frame #16: 0x00002dc5 FanCake-Beta`start + 53

编辑 2：当我尝试打印本地变量时也是如此

(lldb) po currentUser
error: variable not available

如果我在代码中放入一些 NSLog() ，则正确的值正在打印。但不是用po命令。

4

4 回答 4

25

当我打开编译器优化时，我通常会收到此错误。编译器将生成不一定遵循您的代码逻辑流程的代码。

在导航器中转到您的项目 -> 目标 -> 构建设置 -> 搜索优化级别 -> 展开优化级别 -> 选择调试行 -> 在项目和目标的两列中更改为无。

希望这可以帮助。

于 2013-03-08T03:16:37.963 回答
5

我遇到了这个问题，当我编辑我的方案并将运行构建设置为调试时它就消失了。我已经将它设置为 AdHoc 来测试推送通知，这显然让 LLDB 不高兴。

于 2013-03-07T20:04:27.623 回答
5

因为它被优化了。让我们举个例子：

void f(int self) {
  // Here, "self" is live:Its value is used in the call to NSLog()
  NSLog(@"I am %d",self);
  // Here, "self" is dead: Its value is never used.
  // I could do self=0 or self=self*self and nobody would know.
  // An optimizing compiler will typically optimize it away.
  // It might still be on the stack (in the parameters passed to NSLog())
  // but the compiler shouldn't assume this.
  NSLog(@"Another function call: %d", 1);
  // If "self" was on the stack, it will probably now have been overwritten.
}

编译器做了很多事情来让你的代码更快/更小；忘记不再需要的变量是一种非常常见的优化。

于 2013-03-08T04:08:30.463 回答
1

正如在另一个问题中已经说过的：

在构建设置中，将 Precompile Prefix Header 设置为 NO 为我修复了它。

于 2016-05-05T11:19:45.130 回答