What's the difference between a class method and an instance method?
Are instance methods the accessors (getters and setters) while class methods are pretty much everything else?
转载于:https://stackoverflow.com/questions/1053592/what-is-the-difference-between-class-and-instance-methods
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Like most of the other answers have said, instance methods use an instance of a class, whereas a class method can be used with just the class name. In Objective-C they are defined thusly:
@interface MyClass : NSObject
+ (void)aClassMethod;
- (void)anInstanceMethod;
@end
They could then be used like so:
[MyClass aClassMethod];
MyClass *object = [[MyClass alloc] init];
[object anInstanceMethod];
Some real world examples of class methods are the convenience methods on many Foundation classes like NSString's +stringWithFormat: or NSArray's +arrayWithArray:. An instance method would be NSArray's -count method.
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