//下面這段宏考過去直接用
#define SYNTHESIZE_SINGLETON_FOR_HEADER(className) \
\
+ (className *)sharedInstance;\
+ (void)destroyInstance;
//在單例生成之前onceToken = 0,在單例生成之后onceToken = -1了,之后一直保持-1這個值,知道這個之后我想你應該有思路了
#define SYNTHESIZE_SINGLETON_FOR_CLASS(className) \
\
static className *shared##className = nil; \
static dispatch_once_t onceToken;\
+ (className *)sharedInstance\
{\
 return [[self alloc] init];\
}\
+ (className *)allocWithZone:(struct _NSZone *)zone\
{\
 dispatch_once(&onceToken, ^{\
  shared##className = [super allocWithZone:zone];\
 });\
 return shared##className;\
}\
- (className *)copyWithZone:(NSZone *)zone\
{\
 return shared##className;\
}\
- (className *)mutableCopyWithZone:(NSZone *)zone\
{\
 return shared##className;\
}\
+ (void)destroyInstance {\
 shared##className = nil;\
 onceToken = 0;\
}\

//用法，注意要遵循NSCopying,NSMutableCopying 協議
import <Foundation/Foundation.h>
@interface YNHTUserModel : NSObject<NSCopying,NSMutableCopying>
SYNTHESIZE_SINGLETON_FOR_HEADER(YNHTUserModel);
@property (nonatomic,copy) NSString* inviter_id;//邀請人ID
@property (nonatomic,copy) NSString* token;
@property (nonatomic,copy) NSString* nick_name;
@end

#import "YNHTUserModel.h"
@implementation YNHTUserModel
SYNTHESIZE_SINGLETON_FOR_CLASS(YNHTUserModel);

@end