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;}

原文地址：https://www.cnblogs.com/CH520/p/9392998.html