继承芋NSObjest
。。。h。。+ (instancetype)sharePerson;
staticPerson*_person =nil;
+ (instancetype)sharePerson
{
staticdispatch_once_tonceToken;
dispatch_once(&onceToken, ^{
_person= [[Personalloc]init];
});
return_person;
}
写法二
+ (instancetype)alloc
{
staticdispatch_once_tonceToken;
dispatch_once(&onceToken, ^{
//里面的代码只执行一遍
_person= [superalloc];
});
return_person;
}
