单例的宏定义

#define DEFINE_SINGLETON_FOR_HEADER(className) \

\

+ (className *)shared##className;

#define DEFINE_SINGLETON_FOR_CLASS(className) \

\

+ (className *)shared##className { \

static className *shared##className = nil; \

static dispatch_once_t onceToken; \

dispatch_once(&onceToken, ^{ \

shared##className = [[self alloc] init]; \

}); \

return shared##className; \

}

使用时

1.在.h中#import@interface RootViewController : UIViewController

// 单例

DEFINE_SINGLETON_FOR_HEADER(RootViewController);

@end

2.在.m中

#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

#pragma mark - public method

// 单例

DEFINE_SINGLETON_FOR_CLASS(RootViewController)

3.得到单例

RootViewController *controller = [RootViewController sharedRootViewController]