Xcode 中有 var_dump 吗？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19914895/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Is there a var_dump in Xcode?
提问by Arian Faurtosh
I come from a php background... so I was wondering if there was such a thing as var_dumpfor Xcode, I know about NSLogbut I want it to act like var_dump.
我来自 php 背景......所以我想知道是否有像var_dumpXcode这样的东西，我知道NSLog但我希望它像var_dump.
Is there a function for this?
有这个功能吗？
采纳答案by Macondo2Seattle
In code:
在代码中：
NSLog(@"%@", myVar);
which is equivalent to
这相当于
NSLog(@"%@", [myVar description]);
Or in the debugger: right click on the variable, and select "Print description".
或者在调试器中：右键单击变量，然后选择“打印描述”。
If you want to inspect objects of your own classes this way, you need to implement the method -(NSString *)descriptionfor those classes.
如果您想以这种方式检查您自己的类的对象，您需要-(NSString *)description为这些类实现该方法。
回答by little
In swift you can use dump(var) which uses mirror for introspection and useful for classes.
在 swift 中，您可以使用 dump(var) ，它使用镜像进行自省并对类有用。
For example:
例如：
let pet = Pet(name:"Max", age: 4)
let adam = Person(name:"Adam", age: 30, pet:pet)
print("\(pet)")
print("\(adam)")
print("======")
dump(pet)
dump(adam)
The output will be:
输出将是：
Pet
Person
======
? Pet #0
- name: "Max"
- age: 4
? Person #0
- name: "Adam"
- age: 30
? pet: Optional(Pet)
? some: Pet #1
- name: "Max"
- age: 4
回答by Gabriele Petronella
NSObjectdefines the descriptionmethod, which provides a description of the object. The default implementation just prints the name of the class, but it's commonly overridden by subclasses to provide a more meaningful description of their content.
NSObject定义description方法，该方法提供对象的描述。默认实现只打印类的名称，但它通常被子类覆盖以提供对其内容更有意义的描述。
This is for instance the case of NSArrayand NSDictionary, whose implementation produces a NSStringrepresenting the objects stored in the collection.
这是例如NSArrayand的情况NSDictionary，它的实现产生一个NSString代表存储在集合中的对象。
When you do
当你做
NSLog(@"%@", anObject);
descriptionis automatically called on the object to retrieve a textual representation of it.
description自动调用对象以检索它的文本表示。
Also in the debugger you can do
同样在调试器中你可以做
po anObject
to achieve the same result.
达到相同的结果。
Bottom line, if you need to provide a representation of a custom class you implemented, the way to go is to override description.
最重要的是，如果您需要提供您实现的自定义类的表示，那么要走的路是覆盖description.
