问题描述
类方法和实例方法之间的区别是什么?为什么我们需要单独使用它们?有人可以解释一下吗?
Whats the difference between class methods and Instance methods. Why do we need them separately?Can somebody please explain?
类和实例方法
•实例响应实例方法
- (id)init;
- (float)height;
- (void)walk;
•类响应类方法
+ (id)alloc;
+ (id)person;
+ (Person *)sharedPerson;
Taimur
推荐答案
实例方法仅在类的实例上可用，而类方法不需要实例，但在类上可用.
An instance method is only available on an instance of the class, while a class method does not need an instance but is available on the class.
类方法用+表示，而实例方法用其返回类型前的-表示.
Class Methods are denoted by a + while instance methods are denoted by a - before their return type.
让我们以NSObject为例. NSObject具有一个名为+ (id)alloc的类方法. alloc方法用于分配类的实例.显然，alloc必须是一个类方法，因为如果它是一个实例方法，那么您将从何处获得根"实例?
Let's take NSObject for example. NSObject has a class method named + (id)alloc. The alloc method is used to allocate an instance of the class. Obviously alloc must be a class method because if it was an instance method, where would you get the "root" instance from?
另一方面，- (id)init是一种实例方法，因为它可以初始化实例的状态.
On the other hand - (id)init is an instance method because it initializes the state of an instance.
这篇关于差异类和实例方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！