在.h接口中或在.m文件中的扩展中声明属性？

问题描述

在Objective-C中，最佳做法是：

In Objective-C, is it best practice to:

1. 在.h中声明对象在.m中综合。

1. Declare objects such as buttons in the .h and then synthesize in the .m

.h
@interface SomeViewController : UIViewController
  @property (strong, nonatomic) UIButton *someButton;
@end

.m
@implementation SomeViewController
  @synthesize someButton = _someButton;
@end

或在.m中声明为ivars

or declare them as ivars in the .m

@interface SomeViewController ()
  @property (strong, nonatomic) UIButton *someButton;
@end

在很多Apple代码中，特别是他们的Breadcrumbs示例代码，他们的许多属性都在界面中声明。两者之间有区别吗？我还注意到，当属性在 @interface 中声明时，它们会自动以下划线前缀合成，使 someButton = _someButton synthesis useless。

I notice that in a lot of Apple code, specifically their Breadcrumbs sample code, many of their properties are declared in the interface. Is there a difference between the two? I also noticed that when properties are declared in the @interface, they are automatically synthesized with an underscore prefix, making the someButton = _someButton synthesis useless.

推荐答案

首先，起，不再需要 @synthesize 您可以在 @interface 或<$中声明 @property 时更改setter和getter方法c $ c> @implementation 。

First, as of Xcode 4.4 there is no longer a need to @synthesize(unless you change both the setter and getter method), either when the @property is declared in the @interface or @implementation.

如果 @property 然后在。这提供了封装，并且很容易看到 @property 不是从另一个类中使用。

If the @property is only accessed from within the class then declare the @property in a class extension in the .m file. This provides encapsulation and make it easy to see that the @property is not used from another class.

@property 被其他类用于设计，然后在.h文件中的 @interface 中定义。

If the @property is used by other classes, by design, then define it in the @interface in the .h file.

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