如何在 xcode 中创建断点的日志消息操作？
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how to create a breakpoint's log message action in xcode?
提问by PrimeSeventyThree
Been watching a WWDC video today about new features in xCode 4. They have mentioned that it a good idea to use log message actions on breakpoints along with "automatically continue after evaluation actions" enabled to output a variable's value for instance instead of using NSLogs all the time.
今天一直在观看有关 xCode 4 中新功能的 WWDC 视频。他们提到在断点上使用日志消息操作以及启用“评估操作后自动继续”以输出变量的值是个好主意，而不是使用 NSLogs all时间。
lets say I have something like that:
可以说我有这样的事情：
NSLog(@"URL is : %@", userDocumentsURL);
How would I write a log message action to display userDocumentsURL's value? Is it really a good idea to use the above method instead of NSLog?
我将如何编写日志消息操作来显示 userDocumentsURL 的值？用上面的方法代替NSLog真的是个好主意吗？
回答by Josh
Create a Breakpoint 'Log Message' action. For the log message include something like:
创建断点“日志消息”操作。对于日志消息，包括以下内容：
URL is @(char*) [[userDocumentsURL description] UTF8String]@
Alternatively you can create a breakpoint 'Debugger command' action similar to:
或者，您可以创建类似于以下内容的断点“调试器命令”操作：
po [NSString stringWithFormat:@"URL is: %@", userDocumentsURL]
I prefer using breakpoint actions for logging, as it's arguably easier to clear out a bunch of breakpoints than it is to remove NSLogs. A possible downside to using breakpoints in this fashion is that they are significantly slower (during debugging) than a direct NSLog.
我更喜欢使用断点操作进行日志记录，因为可以说清除一堆断点比删除 NSLogs 更容易。以这种方式使用断点的一个可能的缺点是它们比直接 NSLog 慢得多（在调试期间）。
回答by Skotch
Here is a similar solution using NSLog, which might be fewer characters than the other solutions.
这是使用 的类似解决方案NSLog，它可能比其他解决方案的字符少。
However, unless you add the voidlike this:
但是，除非你添加void这样的：
po (void)NSLog(@"the person name is: %@", p.name)
you will get an annoying "nil" printed out with your log. for example:
您会在日志中打印出令人讨厌的“nil”。例如：
(lldb) po NSLog(@"foo")
nil
2013-06-19 14:42:59.025 TheMove[95864:c07] foo
(lldb) po (void)NSLog(@"foo")
2013-06-19 14:43:10.758 TheMove[95864:c07] foo
If you can live with the nil (I can) it's faster to type and easier to remember just the po
如果您可以接受 nil（我可以），那么键入会更快，并且更容易记住 po
回答by Barton Friedland
I notice that the edit breakpoints feature, while useful and perhaps modern, does not commit to source control, so does not scale to a team of developers. For this reason, I would say that when working on a team under source control to stick with code-based logging such as NSLog.
我注意到编辑断点功能虽然有用且可能很现代，但不致力于源代码控制，因此无法扩展到开发团队。出于这个原因，我会说在源代码控制下的团队工作时，坚持使用基于代码的日志记录，例如 NSLog。
