IOS macros define a single case

Sometimes it is because of the frequent creation of a singleton object and headache, one way to write many times? Of course you can use the OC language for encapsulation. However, the following describes a package in C language. As long as the following method is implemented, a singleton object will be built after two sentences.

1. Create a new. h file and implement the following methods in the file:

1/. h2 #defineSingleton_interface (Class) + (Instancetype) shared# #class;3 4 //. M5 #defineSingleton_implementation (Class)6 Static class*_instance;7 8+ (ID) Allocwithzone: (struct_nszone *) Zone9 { Ten     Staticdispatch_once_t Oncetoken; OneDispatch_once (&oncetoken, ^{  A_instance =[Super Allocwithzone:zone]; -     });  -  the     return_instance; - }  -  -+ (Instancetype) shared##class  + {  -     if(_instance = =Nil) {  +_instance = [[classalloc] init];  A     }  at  -     return_instance; -}

2. How to use.

Write the first sentence in the. h file in the class that you want to create the singleton in:

Singleton_interface (class name)
      Write the second sentence in the. m file:

Well, after importing the header file in any project, and then implementing the two sentences in the class, you can easily use the singleton, and no longer have to write a lot of code frequently. Looks like it's not very big on!

IOS macros define a single case