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建议在Objective-C中使用类方法和对象方法的最佳方法？

[英]Suggest best way to use class methods and object methods in Objective-C?

原文 2010-07-30 06:54:47 5 1 objective-c/ oop

I am using both methods in my project, can you please let me know, which one is best for in which situation? 我在项目中同时使用这两种方法，请告诉我，哪种方法最适合哪种情况？

Regards, Sri 问候，斯里

1 个解决方案

Well, completely seriously, class methods should be specific to a class, and instance methods should be specific to an instance. 好吧，完全认真地讲，类方法应该特定于一个类，实例方法应该特定于一个实例。 Think about the method in question; 想想有问题的方法； does it depend on instance variables? 它取决于实例变量吗？ Is it referring to a specific instance of the class in question? 它是指所讨论类的特定实例吗？ Or is it more general than that? 还是比这更笼统？

Frequently, class methods are convenient ways to return instances (for example, [NSColor redColor] is a handy class method for returning a common instance of NSColor ). 通常，类方法是返回实例的便捷方法（例如[NSColor redColor]是用于返回NSColor的公共实例的便捷类方法）。 On the other hand, the instance method -greenComponent (which returns the green component of an RGB color) clearly needs to refer to a specific instance (if I asked you, "how much green is in color?" that wouldn't make sense. It's "how much green is in this color here ?" that is a reasonable question). 另一方面，实例方法-greenComponent （返回RGB颜色的绿色分量）显然需要引用特定的实例（如果我问你“多少颜色是绿色？”），这是没有意义的。是“ 这里的这种颜色有多少绿色？”这是一个合理的问题）。

You can also browse Apple's class references to get a better feel for which sorts of things are class methods (+) vs. instance methods (-). 您还可以浏览Apple的类引用，以更好地了解类方法（+）与实例方法（-）的区别。