NSString：isEqual vs. isEqualToString [英] NSString: isEqual vs. isEqualToString

问题描述

isEqual：与 isEqualToString：有什么区别？

为什么类添加isEqualTo *方法（isEqualToArray用于NSArray，isEqualToData用于NSData，...）而不是仅覆盖 isEqual：？

Why are classes adding isEqualTo* methods (isEqualToArray for NSArray, isEqualToData for NSData, ...) instead of just overriding isEqual: ?

推荐答案

isEqual：将字符串与对象进行比较，并返回 NO 如果对象不是字符串。 isEqualToString：更快，如果你知道两个对象都是字符串，因为文档状态：

isEqual: compares a string to an object, and will return NO if the object is not a string. isEqualToString: is faster if you know both objects are strings, as the documentation states:

特殊注意事项

当你知道这两个对象都是字符串时，方法检查等于 isEqual：。

When you know both objects are strings, this method is a faster way to check equality than isEqual:.

isEqualTo< Class> 用于提供对等式的特定检查。例如; isEqualToArray： 检查数组是否包含相等数量的对象，并且给定索引处的对象返回是 isEqual：测试。

isEqualTo<Class> is used to provide specific checks for equality. For instance; isEqualToArray: checks that the arrays contain an equal number of objects, and that the objects at a given index return YES for the isEqual: test.

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