@synthesize 与使用 self [英] @synthesize vs. use of self

问题描述

我是 iOS 新手，一直在从教程和我的教授那里学习.
在 .h 文件中，我们有:

I am new to iOS, and have been learning from tutorials and from my professor.
In the .h file we have:

@interface ViewController : UIViewController <UITextFieldDelegate>

@property (strong, nonatomic) IBOutlet UILabel *myResponse;
@property (strong, nonatomic) IBOutlet UITextField *myInput;

@end

在 .m 文件中，我们有:

In the .m file we have:

@sysnthesize myResponse
@synthesize myInput

我的问题是:在 .m 文件中，添加 @synthesize 和使用类似 [myInput < 的属性有什么区别;do something here>] 与消除 @synthesize 和使用 [self.myInput <do something here>].我在 Xcode 5 上运行，所以我知道我可以使用自动合成，但是两者之间有更细微的区别吗?

My question is this: What is the difference, in the .m file, between added the @synthesize and then using the properties like [myInput <do something here>] versus eliminating the @synthesize and using [self.myInput <do something here>]. I am running on Xcode 5, so I do understand that I have auto-synthesize available, but is there a more subtle difference between the two?

我的教授使用了 @synthesize 而我所关注的教程只是使用了 self.propertyName，因此我很好奇.

My professor used the @synthesize and the tutorial I was following was just using the self.propertyName, hence I am curious.

谢谢.

推荐答案

您不再需要显式地将 @synthesize 用于属性.如果您的教授正在使用它，那只是为了明确并展示幕后发生的事情.

You no longer have to explicitly use @synthesize for properties. If your professor was using it, it was just to be explicit and demonstrate what's happening under the hood.

如果您的属性在 .h 文件中定义，则会自动生成访问器、修改器和实例变量.如果您明确地@synthesize 这些属性，则可以通过指令后提供的任何 ivar 名称访问它们.如果不使用 @synthesize，自动生成的 ivars 可以通过 _somePropertyName 获得.

If your property is defined in the .h file, accessors, mutators and instance variables are automatically generated. If you explicitly @synthesize those properties, they are accessible via whatever ivar name is provided after the directive. If @synthesize is not used, the automatically generated ivars are available through _somePropertyName.

在您的示例中，使用 @synthesize，myResponse UILabel 可通过实例变量 myResponse 访问.如果没有 @synthesize，它可以通过 _myResponse 获得.在这两种情况下，它都可以通过 self.myResponse 获得.在任何生命周期方法、访问器或修改器(-viewDidLoad、-viewWillAppear、-setMyResponse: 等)中使用实例变量是最佳实践) 并在所有其他方法中使用 self.propertyName 来清楚地区分类的属性和实例变量.

In your example, with the @synthesize, the myResponse UILabel is accessible through the instance variable myResponse. Without the @synthesize, it is available through _myResponse. In both cases, it is available through self.myResponse. It's best practice to use the instance variables in any lifecycle methods, accessors, or mutators (-viewDidLoad, -viewWillAppear, -setMyResponse:, etc) and to use self.propertyName in all other methods to clearly distinguish the properties of a class from the instance variables.

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