xcode +(void) 在objective-c 类静态变量构造函数中初始化
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+(void) initialize in objective-c class static variables constructor
提问by Sagar R. Kothari
I found some sample code from here.
我从这里找到了一些示例代码。
static UIImage *backgroundImageDepressed;
/**
*
*/
@implementation DecimalPointButton
+ (void) initialize {
backgroundImageDepressed = [[UIImage imageNamed:@"decimalKeyDownBackground.png"] retain];
}
Is it something like this - +(void) initializemethod initialize static variables of a class ( interface ) in Objective C? I have never seen this before.
是不是像这样 -+(void) initialize方法在目标 C 中初始化类（接口）的静态变量？我以前从未见过这个。
回答by kennytm
This +initializemethod is described in The Objective-C Programming Language.
该+initialize方法在The Objective-C Programming Language 中有所描述。
The runtime system sends an
initializemessage to every class object before the class receives any other messagesand after its superclass has received theinitializemessage. This gives the class a chance to set up its runtime environment before it's used. If no initialization is required, you don't need to write aninitializemethod to respond to the message.
运行时系统在类接收任何其他消息之前和其超类收到 消息之后，
initialize向每个类对象发送一条消息。这使类有机会在使用之前设置其运行时环境。如果不需要初始化，则不需要编写响应消息的方法。initializeinitialize
For example, when [DecimalPointButton alloc]is called, the runtime will check if [DecimalPointButton initialize]has been called. If not, it will +initializethe class. This ensure the backgroundImageDepressedimage is ready beforeany instances of DecimalPointButton are constructed.
例如，当[DecimalPointButton alloc]被调用时，运行时将检查是否[DecimalPointButton initialize]已被调用。如果没有，它将+initialize上课。这可确保在构建任何 DecimalPointButton 实例之前backgroundImageDepressed图像已准备就绪。
