Perfect single macro definition (compatible with ARC and MRC), which can be used directly in the project

Single-Case mode:
1. Always allocate only one piece of memory to create objects
2. Provide a class method that returns an internally unique object (one instance)
3. It is best to ensure that the Init method is initialized only once

The general wording of the arc under the single example (\ In the code is the definition of the macro):

Static ID_instance;+ (ID) Allocwithzone: (struct_nszone *) zone{Staticdispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{_instance=[Super Allocwithzone:zone];    }); return_instance;}+(instancetype) shared# #name {Staticdispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{_instance=[[Self alloc] init];    }); return_instance;}+ (ID) Copywithzone: (struct_nszone *) zone{return_instance;}

MRC notation:

Static ID_instance;+ (ID) Allocwithzone: (struct_nszone *) Zone {Staticdispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{_instance=[Super Allocwithzone:zone];}); return_instance;} +(instancetype) shared# #name {Staticdispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{_instance=[[Self alloc] init];}); return_instance;} -(OneWayvoid) Release {}- (ID) Autorelease {return_instance;} - (ID) Retain {return_instance;} -(Nsuinteger) retaincount {return 1; } + (ID) Copywithzone: (struct_nszone *) Zone {return_instance;}

The use of macros in a singleton class (. h file):

The use of macros in a singleton class (. m file):

Obviously, the simplification of the single case is greatly improved, which improves the reuse value of the code.

Specific Use effect:

Address of the object to print:

In the work of a single case, every rewrite annoying. Understand the role and wording of the single case, you may try this macro definition, can also propose to modify the common progress

GitHub's

Perfect single macro definition (compatible with ARC and MRC), which can be used directly in the project