在Objective C中使用静态init时的好处？ [英] Benefits when using static init in Objective C?

问题描述

最近我发现了来自Github的webrtc-ios示例。当我浏览项目时，我注意到VideoView类使用的是静态方法，我不确定是否有必要。
VideoView是UIView的子类，它覆盖了两个init方法， initWithFrame：和 initWithCoder：。我知道覆盖这些init方法然后使用一些方法设置其他东西是正常的，比如 - （void）setup; 。

Recently I've discovered webrtc-ios example from Github. While I was browsing though the project I noticed that VideoView class uses static method and I'm not sure is that necessary or not. VideoView is subclass of UIView and it overrides two init methods, initWithFrame: and initWithCoder:. I know it's normal to override those init methods and then use some method for setting up other stuff, like - (void)setup;.

但VideoView类使用静态函数， static void init（VideoView * self）。问题是使用静态函数与普通ObjC方法有什么好处？

But VideoView class uses static function, static void init(VideoView *self). Question is are there benefits when using static function vs. normal ObjC method?

VideoView类中的代码如下所示：

Code in VideoView class looks like this:

-(id)initWithFrame:(CGRect)frame {

     if (self = [super initWithFrame:frame]) {
         init(self);
     }
     return self; 
}

-(id)initWithCoder:(NSCoder *)aDecoder {

     if (self = [super initWithCoder:aDecoder]) {
         init(self);
     }
     return self; 
}

 static void init(VideoView *self) { ... }

推荐答案

使用静态函数和Objective-C方法的一个区别是
静态函数不能在子类中重写。如果公共初始化代码在

$ b

One difference between using a static function and an Objective-C method is that the static function cannot be overriden in a subclass. If the common init code is done in a

- (void)setup;

方法，以及 MyVideoView 的子类 VideoView 碰巧实现了一个同名的方法，然后

method, and a subclass MyVideoView of VideoView happens to implement a method with the same name, then

[[MyVideoView alloc] initWithFrame:..]

将调用可能不需要的子类实现。

will call the subclass implementation, which might not be wanted.

在你的代码中，
initWithFrame / initWithCoder 将始终调用本地 init（）函数，即使
初始化了子类的实例。

In your code, initWithFrame/initWithCoder will always call the local init() function, even if an instance of a subclass is initialized.

如果共同初始化是在方法中完成的，那么方法名称应该更具有
特定，以避免它被意外覆盖，例如

If the common initialization is done in a method, then the method name should be more specific, to avoid that it is overriden "accidentally", for example

-(void)commonVideoViewSetup;

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