一：创建 宏 文件 SynthesizeSingleton.h
SynthesizeSingleton.h #if __has_feature(objc_arc) // ARC Version #define SYNTHESIZE_SINGLETON_FOR_CLASS(classname) \
\
+ (classname *)shared##classname\
{\
static classname *shared##classname = nil;\
static dispatch_once_t onceToken;\
dispatch_once(&onceToken, ^{\
shared##classname = [[classname alloc] init];\
});\
return shared##classname;\
} #else // Non-ARC Version #define SYNTHESIZE_SINGLETON_FOR_CLASS(classname) \
static classname *shared##classname = nil; \
+ (classname *)shared##classname \
{ \
@synchronized(self) \
{ \
if (shared##classname == nil) \
{ \
shared##classname = [[self alloc] init]; \
} \
} \
return shared##classname; \
} \
\
+ (id)allocWithZone:(NSZone *)zone \
{ \
@synchronized(self) \
{ \
if (shared##classname == nil) \
{ \
shared##classname = [super allocWithZone:zone]; \
return shared##classname; \
} \
} \
return nil; \
} \
- (id)copyWithZone:(NSZone *)zone \
{ \
return self; \
} \
- (id)retain \
{ \
return self; \
} \
- (NSUInteger)retainCount \
{ \
return NSUIntegerMax; \
} \
- (oneway void)release \
{ \
} \
- (id)autorelease \
{ \
return self; \
} #endif
二：使用
MyClass.h @interface MyClass : NSObject +(DataStorage *)sharedMyClass; @end
MyClass.m #import "SynthesizeSingleton.h"
@implementation MyClass
SYNTHESIZE_SINGLETON_FOR_CLASS(MyClass)
@end