定义形式 #define  字符串

含参数的 #define a(b) 2*b; 

当需要参数拼接时 用##   #define FunctionTest(a)  -(void)te##a{NSLog(@"test");} 

需要换行时  用\ #define str(a,b,c) {a+=b;a+=c;}

 #define str(a,b,c) {a+=b;\

　　a+=c;}  

////  SynthesizeSingleton.h//  CocoaWithLove////  Created by Matt Gallagher on 20/10/08.//  Copyright 2009 Matt Gallagher. All rights reserved.////  Permission is given to use this source code file without charge in any//  project, commercial or otherwise, entirely at your risk, with the condition//  that any redistribution (in part or whole) of source code must retain//  this copyright and permission notice. Attribution in compiled projects is//  appreciated but not required.//#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; \} \ \