内存管理、单例

1、内存管理

• 1.1 函数、属性定义

/** 定义一个define函数 */
#define TT_RELEASE_CF_SAFELY(__REF) { if (nil != (__REF)) { CFRelease(__REF); __REF = nil; } }
/** 强引用、弱引用 */
#define CHWeakSelf(type)  __weak typeof(type) weak##type = type;
#define CHStrongSelf(type)  __strong typeof(type) type = weak##type;

• 1.2 处理ARC和MRC，对象释放

/** 使用ARC和不使用ARC */
#if __has_feature(objc_arc)
    //compiling with ARC
#else
    // compiling without ARC
#endif

/** 释放一个对象 */
#define SAFE_DELETE(P) if(P) { [P release], P = nil; }

2、单例

• 2.1 单例（合并）

#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; 
}

• 2.2 单例（分开）

#pragma mark 接口.h
#define singleton_interface(className) +(className *)shared##className;

#pragma mark 实现.m
#define singleton_implementation(className) 
static className *_instance;
+(id)shared##className{
if(!_instance){
_instance=[[self alloc]init];
}
return _instance;
}
+(id)allocWithZone:(struct _NSZone *)zone{
static dispatch_once_t dispatchOnce;
dispatch_once(&dispatchOnce, ^{
_instance=[super allocWithZone:zone];
});
return _instance;
}