IOS 单例模式（非ARC）

 singleton_h ：连接字符串和参数

// ## : 连接字符串和参数
#define singleton_h(name) + (instancetype)shared##name;

#define singleton_m(name) \
static id _instance; \
+ (id)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; \
} \
 \
- (oneway void)release \
{ \
 \
} \
 \
- (id)autorelease \
{ \
    return _instance; \
} \
 \
- (id)retain \
{ \
    return _instance; \
} \
 \
- (NSUInteger)retainCount \
{ \
    return 1; \
} \
 \
+ (id)copyWithZone:(struct _NSZone *)zone \
{ \
    return _instance; \
}

调用单例模式  Singleton.h /.m

#import <Foundation/Foundation.h>
#import "Singleton.h"

@interface HMMainTool : NSObject
singleton_h(MainTool)
@end

#import "HMMainTool.h"

@implementation HMMainTool
singleton_m(MainTool)
@end

调用类

#import "HMViewController.h"
#import "HMAudioTool.h"
#import "HMNetTool.h"
#import "HMMainTool.h"

@interface HMViewController ()

@end

@implementation HMViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    HMAudioTool *audio1 = [[HMAudioTool alloc] init];
    HMAudioTool *audio2 = [HMAudioTool sharedAudioTool];
    NSLog(@"1111%p %p", audio1, audio2);
    
    HMNetTool *net1 = [[HMNetTool alloc] init];
    HMNetTool *net2 = [HMNetTool sharedNetTool];
    NSLog(@"2222%p %p", net1, net2);
    
    HMMainTool *main1 = [[HMMainTool alloc] init];
    HMMainTool *main2 = [HMMainTool sharedMainTool];
    NSLog(@"333%p %p", main1, main2);
}

@end