NSString: isEqual vs. isEqualToString

objective-c iphone cocoa nsstring
Jaka Jančar picture Jaka Jančar · Aug 18, 2009 · Viewed 41.1k times · Source

What is the difference between isEqual: and isEqualToString:?

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

Answer

Abizern picture Abizern · Aug 18, 2009

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:

Special Considerations

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

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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