Objective-C Xcode4中的调试提示？ [英] Objective-C Debugging tips in Xcode4?

问题描述

从Flex-Flash IDE开始，我可以在代码中设置断点，并在运行时查看相应窗口中的变量值。

Coming from a Flex-Flash IDE, I was able to set breakpoints in my code and at runtime view the values of my variables in the corresponding window.

现在，我想出在哪里可以找到Xcode中的'变量'窗口，我可以看到我所有的变量，但是这些变量的值不能被看到。我所有的是数据类型和一堆十六进制数（指针？）。

Now, I figured out where I can find the 'variables' window in Xcode and I can see all my variables there BUT the values of those variables can't be seen. All I have is the data type and a bunch of hex numbers (pointers?).

我应该如何调试我的代码？我在哪里可以看到我的变量的值，而不必在代码中登录？

How am I supposed to debug my code? Where can I see the values of my variables without having to log them in my code?

我试图看到一个 NSDictionary 与一堆键/值对。而且还有任何其他 NSObject 。我读了一些关于覆盖描述方法的东西，但是本地对象呢？

I am trying to see the values of a NSDictionary with a bunch of key/value pairs. But also any other NSObject for that matter. I have read something about overriding the description method but what about native objects?

推荐答案

使用GDB进行调试

XCode给你一个GDB Debugger，所以就像Jano在他的评论中说的那样，你可以使用像po（print object）这样的GDB命令查看一个对象。

Debugging with GDB

XCode gives you a GDB Debugger, so like Jano said in his comment, you can use GDB commands like po (print object) to view an object.

po myObject
po myDictionary
po myArray

要打印像int，float这样的基元可以使用 print ， p 和 px （查看十六进制数）

To print primitives like int, float, you can use print, p, and px (to view the number in hex)

print myInt
p myInt
px myInt

您还可以看到运行命令的结果。例如，要查看可以执行的字符串长度：

You can also see the result of running commands. For example, to view a string length you could do:

p (int) [myString length]

如果您没有将返回值转换为int，我相信您会在控制台中看到一些抱怨。

If you do not cast the return to an int, I believe you'll see some complaining in the console.

要查看UIView的框架（CGRect结构类型），您可以执行以下操作：

To view a UIView's frame (CGRect struct type), you can do:

p (CGRect) [myView frame]

最后，如果您覆盖描述方法，您可以自定义在写入控制台时甚至是NSLog的显示方式。如果你做了 [NSString stringWithFormat：@我的对象...％@，myObj] 该对象的描述方法将被调用。

Lastly, if you override the description method of a class, you can customize how it displays when written to the console or even to an NSLog for that matter. If you do [NSString stringWithFormat:@"My object... %@", myObj] the description method of that object will be called.

- (NSString*) description
{
   return @"This is the object description!";
}

另一个好的阅读是如何根据对象字符串属性在Xcode中设置条件断点？

如果您想要NSLog消息，但只能在调试版本中，您可能希望 DLog 我们在我的工作中使用：

If you want NSLog messages but only in debug builds, you might like the DLog macro we use at my work:

#ifdef DEBUG
    #define DLog(...) NSLog(__VA_ARGS__)
#else
    #define DLog(...) /* */
#endif

它的工作原理就像NSLog一样，除了它在非DEBUG构建之外编译。 NSLog实际上可能是一个性能指标，加上您可能不希望某些消息在您的日志中溢出。

It works just like NSLog except that it is compiled out on non-DEBUG builds. NSLog can actually be a performance hit, plus you may not want some messages spilling out in your logs.

我们将这个宏放在预编译头文件（MyApp-Prefix.pch）中，以便它被包含在所有项目文件中。

We put this macro in the precompiled header file (MyApp-Prefix.pch) so that it gets included in all the project files.

您的评论询问如何在不编写代码的情况下转储对象的所有变量。我知道没有内在的方法来做到这一点。但是，您可以尝试使用反射。我有一个实现，可以让你做一些像：

Your comment asked about how to dump all variables of an object without writing code. I know of no built in way to do this. However, you might try using reflection. I have an implementation that will allow you to do something like:

po [someObj dump]

您可以在NSObject上创建一个类别，以将所有NSObject类型的方法添加到将要转储的信息。我从目标C内省/反思借来的代码开始了代码，但是添加代码以包含属性值。

You can make a category on NSObject to add a method to all NSObject types that will dump the information you're after. I borrowed code from Objective C Introspection/Reflection to start off the code, but added code to include property values.

NSObject（DebuggingAid）类别：

NSObject (DebuggingAid) category:

#import <objc/runtime.h>
@interface NSObject (DebuggingAid)

- (NSString*)dump;

@end

@implementation NSObject (DebuggingAid)

- (NSString*)dump
{
    if ([self isKindOfClass:[NSNumber class]] ||
        [self isKindOfClass:[NSString class]] ||
        [self isKindOfClass:[NSValue class]])
    {
        return [NSString stringWithFormat:@"%@", self];
    }

    Class class = [self class];
    u_int count;

    Ivar* ivars = class_copyIvarList(class, &count);
    NSMutableDictionary* ivarDictionary = [NSMutableDictionary dictionaryWithCapacity:count];
    for (int i = 0; i < count ; i++)
    {
        const char* ivarName = ivar_getName(ivars[i]);
        NSString *ivarStr = [NSString stringWithCString:ivarName encoding:NSUTF8StringEncoding];
        id obj = [self valueForKey:ivarStr];
        if (obj == nil)
        {
            obj = [NSNull null];
        }
        [ivarDictionary setObject:obj forKey:ivarStr];
    }
    free(ivars);

    objc_property_t* properties = class_copyPropertyList(class, &count);
    NSMutableDictionary* propertyDictionary = [NSMutableDictionary dictionaryWithCapacity:count];
    for (int i = 0; i < count ; i++)
    {
        const char* propertyName = property_getName(properties[i]);
        NSString *propertyStr = [NSString  stringWithCString:propertyName encoding:NSUTF8StringEncoding];
        id obj = [self valueForKey:propertyStr];
        if (obj == nil)
        {
            obj = [NSNull null];
        }
        [propertyDictionary setObject:obj forKey:propertyStr];
    }
    free(properties);

    NSDictionary* classDump = [NSDictionary dictionaryWithObjectsAndKeys:
                               ivarDictionary, @"ivars",
                               propertyDictionary, @"properties",
                               nil];
    NSString *dumpStr = [NSString stringWithFormat:@"%@", classDump];

    return dumpStr;
}

@end

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