作为一名开发人员，在开发过程中如果将常用的代码收集起来，添加到Xcode的代码片库里，通过快捷键直接使用，从而提高开发效率；或者封装为宏或封装在一个类中，可提高代码的复用性。

1） 将常用代码片段封装成一个类里

当一个代码片在一个或多个工程之中经常出现时，把他封装在一个类里面，在使用时候直接传参即可实现对应功能，或者直接把这个类放到另一个工程中同样使用。

#define NavigationBar_HEIGHT 44 #define SCREEN_WIDTH ([UIScreen mainScreen].bounds.size.width)#define SCREEN_HEIGHT ([UIScreen mainScreen].bounds.size.height)#define SAFE_RELEASE(x) [x release];x=nil#define IOS_VERSION [[[UIDevice currentDevice] systemVersion] floatValue]#define CurrentSystemVersion ([[UIDevice currentDevice] systemVersion])#define CurrentLanguage ([[NSLocale preferredLanguages] objectAtIndex:0]) #define BACKGROUND_COLOR [UIColor colorWithRed:242.0/255.0 green:236.0/255.0 blue:231.0/255.0 alpha:1.0] //use dlog to print while in debug model#ifdef DEBUG# define DLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);#else# define DLog(...)#endif #define isRetina ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 960), [[UIScreen mainScreen] currentMode].size) : NO)#define iPhone5 ([UIScreen instancesRespondToSelector:@selector(currentMode)] ? CGSizeEqualToSize(CGSizeMake(640, 1136), [[UIScreen mainScreen] currentMode].size) : NO)#define isPad (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) #if TARGET_OS_IPHONE//iPhone Device#endif #if TARGET_IPHONE_SIMULATOR//iPhone Simulator#endif //ARC#if __has_feature(objc_arc) //compiling with ARC#else // compiling without ARC#endif //G－C－D#define BACK(block) dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), block)#define MAIN(block) dispatch_async(dispatch_get_main_queue(),block) #define USER_DEFAULT [NSUserDefaults standardUserDefaults]#define ImageNamed(_pointer) [UIImage p_w_picpathNamed:[UIUtil p_w_picpathName:_pointer]] #pragma mark - common functions#define RELEASE_SAFELY(__POINTER) { [__POINTER release]; __POINTER = nil; } #pragma mark - degrees/radian functions#define degreesToRadian(x) (M_PI * (x) / 180.0)#define radianToDegrees(radian) (radian*180.0)/(M_PI) #pragma mark - color functions#define RGBCOLOR(r,g,b) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:1]#define RGBACOLOR(r,g,b,a) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:(a)]#define ITTDEBUG#define ITTLOGLEVEL_INFO 10#define ITTLOGLEVEL_WARNING 3#define ITTLOGLEVEL_ERROR 1 #ifndef ITTMAXLOGLEVEL #ifdef DEBUG #define ITTMAXLOGLEVEL ITTLOGLEVEL_INFO#else #define ITTMAXLOGLEVEL ITTLOGLEVEL_ERROR#endif #endif // The general purpose logger. This ignores logging levels.#ifdef ITTDEBUG #define ITTDPRINT(xx, ...) NSLog(@"%s(%d): " xx, __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__)#else #define ITTDPRINT(xx, ...) ((void)0)#endif // Prints the current method's name.#define ITTDPRINTMETHODNAME() ITTDPRINT(@"%s", __PRETTY_FUNCTION__) // Log-level based logging macros.#if ITTLOGLEVEL_ERROR <= ITTMAXLOGLEVEL #define ITTDERROR(xx, ...) ITTDPRINT(xx, ##__VA_ARGS__)#else #define ITTDERROR(xx, ...) ((void)0)#endif #if ITTLOGLEVEL_WARNING <= ITTMAXLOGLEVEL #define ITTDWARNING(xx, ...) ITTDPRINT(xx, ##__VA_ARGS__)#else #define ITTDWARNING(xx, ...) ((void)0)#endif #if ITTLOGLEVEL_INFO <= ITTMAXLOGLEVEL #define ITTDINFO(xx, ...) ITTDPRINT(xx, ##__VA_ARGS__)#else #define ITTDINFO(xx, ...) ((void)0)#endif #ifdef ITTDEBUG #define ITTDCONDITIONLOG(condition, xx, ...) { if ((condition)) { \ ITTDPRINT(xx, ##__VA_ARGS__); \ } \ } ((void)0)#else #define ITTDCONDITIONLOG(condition, xx, ...) ((void)0)#endif #define ITTAssert(condition, ...) \do { \ if (!(condition)) { \ [[NSAssertionHandler currentHandler] \ handleFailureInFunction:[NSString stringWithUTF8String:__PRETTY_FUNCTION__] \ file:[NSString stringWithUTF8String:__FILE__] \ lineNumber:__LINE__ \ description:__VA_ARGS__]; \ } \} while(0) 会员：鸡累基类鸡肋#define LOADIMAGE(file,ext) [UIImage p_w_picpathWithContentsOfFile:[[NSBundle mainBundle]pathForResource:file ofType:ext]]读取本地图片的 和p_w_picpathNamed一样，但是性能比后者要强很多，两个参数，前面一个是 文件名，后面一个是类型例如 p_w_picpathView.p_w_picpath = LOADIMAGE(@"文件名",@"png"); 会员：anglepro#define WIDTH [[UIScreen mainScreen] bounds].size.width#define HEIGHT [[UIScreen mainScreen] bounds].size.height 会员：l20061642#define VIEWWITHTAG(_OBJECT, _TAG) [_OBJECT viewWithTag : _TAG]会员：pri_est#define MyLocal(x, ...) NSLocalizedString(x, nil)这样就不需要填默认的参数了. 对于需要反复使用的方法比较方便。比如说MyLocal(@"0094") 代替了NSLocalizedString(@"0094", nil) 会员：oopp引用第1楼鸡累基类鸡肋于2013-03-26 14:58发表的 :#define LOADIMAGE(file,ext) [UIImage p_w_picpathWithContentsOfFile:[[NSBundle mainBundle]pathForResource:file ofType:ext]]读取本地图片的 和p_w_picpathNamed一样，但是性能比后者要强很多，两个参数，前面一个是 文件名，后面一个是类型例如 p_w_picpathView.p_w_picpath = LOADIMAGE(@"文件名",@"png");在资源不吃紧的情况下,这种反而是个累赘,因为没有缓存.p_w_picpathnamed只是说要缓存,而且无法手动清空而已.缓存是好是坏,只能自己判定. 会员：beyondvincent// rgb颜色转换（16进制->10进制）#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0] [2013.6.9更新] 会员：favormm 检查系统版本我也来一个我用过的，检查系统版本的 1.2.#define SYSTEM_VERSION_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)3.#define SYSTEM_VERSION_GREATER_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)4.#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)5.#define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)6.#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending) 会员：linux_fay//清除背景色#define CLEARCOLOR [UIColor clearColor] //定义UIImage对象#define IMAGE(A) [UIImage p_w_picpathWithContentsOfFile:[[NSBundle mainBundle] pathForResource:A ofType:nil]] //带有RGBA的颜色设置#define COLOR(R, G, B, A) [UIColor colorWithRed:R/255.0 green:G/255.0 blue:B/255.0 alpha:A] //方正黑体简体字体定义#define FONT(F) [UIFont fontWithName:@"FZHTJW--GB1-0" size:F] //安全删除对象#define SAFE_DELETE(P) if(P) { [P release], P = nil; } //接口API#define APIURL @"http://xxxxx/"//登录#define APILogin [APIURL stringByAppendingString:@"Login"] //登录API 会员：tmxk12388// 获取RGB颜色#define RGBA(r,g,b,a) [UIColor colorWithRed:r/255.0f green:g/255.0f blue:b/255.0f alpha:a]#define RGB(r,g,b) RGBA(r,g,b,1.0f) 会员：legnaflow最近我也开始整理常用的，目前只有ALog DLog的https://github.com/linktoming/MMMacro推荐放在github上管理，大家fock 然后根据各自的需要修改和github的gitignore一样 会员：benjaminetw//单例化一个类#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; \}附上原作者声明...//// 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.// 会员：mapper#if DEBUG#define NSLog(FORMAT, ...) fprintf(stderr,"\nfunction:%s line:%d content:%s\n", __FUNCTION__, __LINE__, [[NSString stringWithFormat:FORMAT, ##__VA_ARGS__] UTF8String]);#else#define NSLog(FORMAT, ...) nil#endif主要是格式化了内容

参考连接：

http://www.cocoachina.com/applenews/devnews/2013/0328/5907.html