iOS中常见的一些宏

1.处理NSLog事件(开发者模式打印,发布者模式不打印)
#ifdef DEBUG
#define NSLog(FORMAT, ...) fprintf(stderr,"%s:%d\t%s\n",[[[NSString stringWithUTF8String:FILE] lastPathComponent] UTF8String], LINE, [[NSString stringWithFormat:FORMAT, ##VA_ARGS] UTF8String]);
#else
#define NSLog(FORMAT, ...) nil
#endif
2.在OC语言的情况下导入某些头文件
#ifdef OBJC
//导入头文件
#endif
3.处理循环引用问题(处理当前类对象)
#define WS(weakSelf) __weak __typeof(&*self)weakSelf = self;
4.获取屏幕宽高
#define ScreenWidth [[UIScreen mainScreen] bounds].size.width
#define ScreenHeight [[UIScreen mainScreen] bounds].size.heigh
5.判断iOS8或更高系统版本(该方法仅支持iOS10以下版本,谨慎使用,floatValue是不靠谱的,具体原因请看:http://www.jianshu.com/p/528897755dc8)
#define IOS8UP ([[UIDevice currentDevice].systemVersion floatValue] >= 8)
6.设置颜色RGB值
#define RGB(a,b,c) [UIColor colorWithRed:(a/255.0) green:(b/255.0) blue:(c/255.0) alpha:1.0]
7.设置颜色RGB值+透明度
#define RGBA(a,b,c,d) [UIColor colorWithRed:(a/255.0) green:(b/255.0) blue:(c/255.0) alpha:d]
8.支持横屏
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000 // 当前Xcode支持iOS8及以上
#define SCREEN_WIDTH ([[UIScreen mainScreen] respondsToSelector:@selector(nativeBounds)]?[UIScreen mainScreen].nativeBounds.size.width/[UIScreen mainScreen].nativeScale:[UIScreen mainScreen].bounds.size.width)
#define SCREENH_HEIGHT ([[UIScreen mainScreen] respondsToSelector:@selector(nativeBounds)]?[UIScreen mainScreen].nativeBounds.size.height/[UIScreen mainScreen].nativeScale:[UIScreen mainScreen].bounds.size.height)
#define SCREEN_SIZE ([[UIScreen mainScreen] respondsToSelector:@selector(nativeBounds)]?CGSizeMake([UIScreen mainScreen].nativeBounds.size.width/[UIScreen mainScreen].nativeScale,[UIScreen mainScreen].nativeBounds.size.height/[UIScreen mainScreen].nativeScale):[UIScreen mainScreen].bounds.size)
#else
#define SCREEN_WIDTH [UIScreen mainScreen].bounds.size.width
#define SCREENH_HEIGHT [UIScreen mainScreen].bounds.size.height
#define SCREEN_SIZE [UIScreen mainScreen].bounds.size
#endif
9.设置随机颜色
#define LRRandomColor [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1.0]
10.设置view的圆角边框
#define LRViewBorderRadius(View, Radius, Width, Color)

[View.layer setCornerRadius:(Radius)];
[View.layer setMasksToBounds:YES];
[View.layer setBorderWidth:(Width)];
[View.layer setBorderColor:[Color CGColor]]
11.获取图片资源
#define kGetImage(imageName) [UIImage imageNamed:[NSString stringWithFormat:@"%@",imageName]]

12.获取当前语言
#define LRCurrentLanguage ([[NSLocale preferredLanguages] objectAtIndex:0])
13.判断当前的iPhone设备/系统版本

//判断是否为iPhone
#define IS_IPHONE (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
//判断是否为iPad
#define IS_IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
//判断是否为ipod
#define IS_IPOD ([[[UIDevice currentDevice] model] isEqualToString:@"iPod touch"])
// 判断是否为 iPhone 5SE
#define iPhone5SE [[UIScreen mainScreen] bounds].size.width == 320.0f && [[UIScreen mainScreen] bounds].size.height == 568.0f
// 判断是否为iPhone 6/6s
#define iPhone6_6s [[UIScreen mainScreen] bounds].size.width == 375.0f && [[UIScreen mainScreen] bounds].size.height == 667.0f
// 判断是否为iPhone 6Plus/6sPlus
#define iPhone6Plus_6sPlus [[UIScreen mainScreen] bounds].size.width == 414.0f && [[UIScreen mainScreen] bounds].size.height == 736.0f
//获取系统版本
#define IOS_SYSTEM_VERSION [[[UIDevice currentDevice] systemVersion] floatValue]

14.判断是真机还是模拟器
#if TARGET_OS_IPHONE
//iPhone Device
#endif
#if TARGET_IPHONE_SIMULATOR
//iPhone Simulator
#endif
15.沙盒目录文件

//获取temp
#define kPathTemp NSTemporaryDirectory()
//获取沙盒 Document
#define kPathDocument [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]
//获取沙盒 Cache
#define kPathCache [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject]

16.宏与const 的使用

很多小伙伴在定义一个常量字符串，都会定义成一个宏，最典型的例子就是服务器的地址。在此所有用宏定义常量字符的小伙伴以后就用const来定义吧！为什么呢 ？我们看看：

宏的用法：一般字符串抽成宏，代码抽成宏使用。
const用法：一般常用的字符串定义成const（对于常量字符串苹果推荐我们使用const）。
宏与const区别：

1.编译时刻不同，宏属于预编译 ，const属于编译时刻

2.宏能定义代码，const不能，多个宏对于编译会相对时间较长，影响开发效率，调试过慢，const只会编译一次，缩短编译时间。

3.宏不会检查错误，const会检查错误

通过以上对比，我们以后在开发中如果定义一个常量字符串就用const，定义代码就用宏。

static NSString * const loginAccount = @"loginAccount";

static NSString * const loginPassword = @"loginPassword";

17.单例化一个类

//
//  SynthesizeSingleton.h
//  CES

#ifndef SynthesizeSingleton_h
#define SynthesizeSingleton_h

 //声明
#define DECLARE_SYNTHESIZE_SINGLETON_FOR_CLASS(classname) \
\
  + (classname *)sharedInstance; \
\


//实现
#define IMPLEMENT_SYNTHESIZE_SINGLETON_FOR_CLASS(classname) \
\
 static classname *shared##classname = nil; \
\
+ (classname *)sharedInstance \
 { \
    @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; \
} \
\

使用方法:在你需要创建单例类的类的.h和.m文件中分别加入以下代码(首先导入以上代码所处的头文件)

 DECLARE_SYNTHESIZE_SINGLETON_FOR_CLASS(LoginManager)(.h)声明
 IMPLEMENT_SYNTHESIZE_SINGLETON_FOR_CLASS(LoginManager)(.m)实现

18.字符串是否为空
#define kStringIsEmpty(str) ([str isKindOfClass:[NSNull class]] || str == nil || [str length] < 1 ? YES : NO )
19.数组是否为空
#define kArrayIsEmpty(array) (array == nil || [array isKindOfClass:[NSNull class]] || array.count == 0)
20.字典是否为空
#define kDictIsEmpty(dic) (dic == nil || [dic isKindOfClass:[NSNull class]] || dic.allKeys == 0)
21.是否是空对象
#define kObjectIsEmpty(_object) (_object == nil
|| [_object isKindOfClass:[NSNull class]]
|| ([_object respondsToSelector:@selector(length)] && [(NSData *)_object length] == 0)
|| ([_object respondsToSelector:@selector(count)] && [(NSArray *)_object count] == 0))

有问题欢迎指正!!本章内容也会持续更新!谢谢!