iOS 单例模式简单实例

#ifndef Singleton_h
#define Singleton_h

@interface Singleton : NS 
@property (nonatomic, copy) NSString *pass;
+ (Singleton *) sharedInstance;

@end

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

@implementation Singleton
static id sharedSingleton = nil;
+ (id)allocWithZone:(struct _NSZone *)zone
{
if (sharedSingleton == nil) {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedSingleton = [super allocWithZone:zone];    
});
}
return sharedSingleton;
}

- (id)init
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedSingleton = [super init];
    });
    return sharedSingleton;
}

+ (instancetype)sharedInstance
{
return [[self alloc] init];
}
+ (id)copyWithZone:(struct _NSZone *)zone
{
return sharedSingleton;
}
+ (id)mutableCopyWithZone:(struct _NSZone *)zone
{
return sharedSingleton;
}


@end

#ifndef Singleton_m_h
#define Singleton_m_h

// 帮助实现单例设计模式

// .h文件的实现
#define SingletonH(methodName) + (instancetype)shared##methodName;

// .m文件的实现
#if __has_feature(objc_arc) // 是ARC
#define SingletonM(methodName) \\
static id _instace = nil; \\
+ (id)allocWithZone:(struct _NSZone *)zone \\
{ \\
if (_instace == nil) { \\
static dispatch_once_t onceToken; \\
dispatch_once(&onceToken, ^{ \\
_instace = [super allocWithZone:zone]; \\
}); \\
} \\
return _instace; \\
} \\
\\
- (id)init \\
{ \\
static dispatch_once_t onceToken; \\
dispatch_once(&onceToken, ^{ \\
_instace = [super init]; \\
}); \\
return _instace; \\
} \\
\\
+ (instancetype)shared##methodName \\
{ \\
return [[self alloc] init]; \\
} \\
+ (id)copyWithZone:(struct _NSZone *)zone \\
{ \\
return _instace; \\
} \\
\\
+ (id)mutableCopyWithZone:(struct _NSZone *)zone \\
{ \\
return _instace; \\
}

#else // 不是ARC

#define SingletonM(methodName) \\
static id _instace = nil; \\
+ (id)allocWithZone:(struct _NSZone *)zone \\
{ \\
if (_instace == nil) { \\
static dispatch_once_t onceToken; \\
dispatch_once(&onceToken, ^{ \\
_instace = [super allocWithZone:zone]; \\
}); \\
} \\
return _instace; \\
} \\
\\
- (id)init \\
{ \\
static dispatch_once_t onceToken; \\
dispatch_once(&onceToken, ^{ \\
_instace = [super init]; \\
}); \\
return _instace; \\
} \\
\\
+ (instancetype)shared##methodName \\
{ \\
return [[self alloc] init]; \\
} \\
\\
- (oneway void)release \\
{ \\
\\
} \\
\\
- (id)retain \\
{ \\
return self; \\
} \\
\\
- (NSUInteger)retainCount \\
{ \\
return 1; \\
} \\
+ (id)copyWithZone:(struct _NSZone *)zone \\
{ \\
return _instace; \\
} \\
\\
+ (id)mutableCopyWithZone:(struct _NSZone *)zone \\
{ \\
return _instace; \\
}
#endif /* Singleton_m_h */