iOS开发常用的宏

#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]
 
#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   WIDTH   [[UIScreen mainScreen] bounds].size.width
#define  HEIGHT  [[UIScreen mainScreen] bounds].size.height