IOS 开发中常用的宏

//release屏蔽NSLog
//放在.pch文件里
#ifdef DEBUG


#else
#define NSLog(...) {};
#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)


//Device
#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)

//区分模拟器和真机

#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