iOS单例

// .h文件
#define XMGSingletonH(name) + (instancetype)shared##name;

// .m文件
#define XMGSingletonM(name) \
static id _instance; \
\
+ (instancetype)allocWithZone:(struct _NSZone *)zone \
{ \
static dispatch_once_t onceToken; \
dispatch_once(&onceToken, ^{ \
_instance = [super allocWithZone:zone]; \
}); \
return _instance; \
} \
\
+ (instancetype)shared##name \
{ \
static dispatch_once_t onceToken; \
dispatch_once(&onceToken, ^{ \
_instance = [[self alloc] init]; \
}); \
return _instance; \
} \
\
- (id)copyWithZone:(NSZone *)zone \
{ \
return _instance; \
}

//person.h 文件
#import <Foundation/Foundation.h>
#import "singleton.h"//包含宏的头文件

@interface person : NSObject
XMGSingletonH(person)
@end

//person.m
#import "person.h"

@interface person()

@end

@implementation person
XMGSingletonM(person)
@end
//这样就完成了person这个类的单例化。