单例宏定义

//
//  QGSingleton.h
//  单例联系
//
//  Created by 李超群 on 16/6/12.
//  Copyright © 2016年 李超群. All rights reserved.
//


/** 单例对外的类方法 */
#define QGSingletonH + (instancetype)sharedInstance;


/** 单例类方法的实现 */
#define QGSingletonM \
static id g_instance; \
 \
+ (instancetype)sharedInstance{ \
    static dispatch_once_t onceToken; \
    dispatch_once(&onceToken, ^{ \
        g_instance = [[self alloc]init]; \
    }); \
    return g_instance; \
} \
 \
 \
+(instancetype)allocWithZone:(struct _NSZone *)zone{ \
    static dispatch_once_t onceToken; \
    dispatch_once(&onceToken, ^{ \
        g_instance = [super allocWithZone:zone]; \
    }); \
    return g_instance; \
} \
 \
 \
- (id)copyWithZone:(NSZone *)zone{ \
    return g_instance; \

}

调用时候就是以下的方法

.h中

#import

#import "QGSingleton.h"
@interface ViewController : UIViewController

QGSingletonH

@end

.m 中

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

QGSingletonM

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end