非ARC和ARC下创建单利模式的宏定义,可以直接套用
本例子是将创建单例模式的.h和.m文件抽出来,用一个宏来定义,放在头文件中:
// 帮助实现单例设计模式 // .h文件的实现 #define SingletonH(methodName) + (instancetype)shared##methodName; // .m文件的实现 #if __has_feature(objc_arc) // 是ARC #define SingletonM(methodName) \ static id _instace = nil; \ + (id)allocWithZone:(struct _NSZone *)zone \ { \ if (_instace == nil) { \ static dispatch_once_t onceToken; \ dispatch_once(&onceToken, ^{ \ _instace = [super allocWithZone:zone]; \ }); \ } \ return _instace; \ } \ \ - (id)init \ { \ static dispatch_once_t onceToken; \ dispatch_once(&onceToken, ^{ \ _instace = [super init]; \ }); \ return _instace; \ } \ \ + (instancetype)shared##methodName \ { \ return [[self alloc] init]; \ } \ + (id)copyWithZone:(struct _NSZone *)zone \ { \ return _instace; \ } \ \ + (id)mutableCopyWithZone:(struct _NSZone *)zone \ { \ return _instace; \ } #else // 不是ARC #define SingletonM(methodName) \ static id _instace = nil; \ + (id)allocWithZone:(struct _NSZone *)zone \ { \ if (_instace == nil) { \ static dispatch_once_t onceToken; \ dispatch_once(&onceToken, ^{ \ _instace = [super allocWithZone:zone]; \ }); \ } \ return _instace; \ } \ \ - (id)init \ { \ static dispatch_once_t onceToken; \ dispatch_once(&onceToken, ^{ \ _instace = [super init]; \ }); \ return _instace; \ } \ \ + (instancetype)shared##methodName \ { \ return [[self alloc] init]; \ } \ \ - (oneway void)release \ { \ \ } \ \ - (id)retain \ { \ return self; \ } \ \ - (NSUInteger)retainCount \ { \ return 1; \ } \ + (id)copyWithZone:(struct _NSZone *)zone \ { \ return _instace; \ } \ \ + (id)mutableCopyWithZone:(struct _NSZone *)zone \ { \ return _instace; \ } #endif