iOS difference between isKindOfClass and isMemberOfClass

Question

What is the difference between the isKind(of aClass: AnyClass) and the isMember(of aClass: AnyClass) functions in Swift?

Original Question in Objective-C

What is the difference between the isKindOfClass:(Class)aClass and the isMemberOfClass:(Class)aClass functions? I know it is something small like, one is global while the other is an exact class match but I need someone to specify which is which please.

Solution 1

isKindOfClass: returns YES if the receiver is an instance of the specified class or an instance of any class that inherits from the specified class.

isMemberOfClass: returns YES if, and only if, the receiver is an instance of the specified class.

Most of the time you want to use isKindOfClass: to ensure that your code also works with subclasses.

The NSObject Protocol Reference talks a little more about these methods.

Solution 2

• isKindOfClass: indicates whether an object inherits from a given class
• isMemberOfClass: indicates whether an object is an instance of a given class.

---

[[NSMutableData data] isKindOfClass:[NSData class]]; // YES
[[NSMutableData data] isMemberOfClass:[NSData class]]; // NO

Solution 3

Suppose

@interface A : NSObject 
@end

@interface B : A
@end

...

id b = [[B alloc] init];

then

[b isKindOfClass:[A class]] == YES;
[b isMemberOfClass:[A class]] == NO;

Basically, -isMemberOfClass: is true if the instance is exactly of the specified class, while -isKindOfClass: is true if the instance is exactly of the specified class or if one of the instance's ancestors is of the specified class.

-isMemberOfClass: is seldom used.

Solution 4

isKindOfClass: Returns a Boolean value that indicates whether the receiver is an instance of given class or an instance of any class that inherits from that class.

isMemberOfClass: Returns a Boolean value that indicates whether the receiver is an instance of a given class.

Solution 5

isKindOfClass-> return YES when the object is instance of that class or instance of a class which is inherited from it.

isMemberOfClass: return YES when the object is instance of that class but No in case: instance of a class which is inherited from it.

example is good enough in jtbandes answer.

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Comments

[poncha]

@Durga, if this answers your question, you should accept it. Read more about accepting rate here: meta.stackexchange.com/questions/16721/…

[PruitIgoe]

But if you have an array of subviews which include UIViews and a UISegmentedControl and you looped through them and set a conditional on class you would need to use isMemberOfClas UIView and isMemberOfClass UISegmentedControl to distinguish between them, no? isKindOfClass would see the UISegmentedControl as a UIView.

[NoodleOfDeath]

@Pruitlgoe that is very true. You might use isKindOfClass:[UIView class] to ensure that all objects you are dealing with are UIViews but you would need to use isMemberOfClass:[UIView class] and/or isMemberOfClass:[UISegmentedControl class] inside some conditional statement to indicate any distinct implementation of the views based on their immediate instance class

[Nikkie]

Can you please clear my below doubt? if ([lbl.textColor isMemberOfClass:[UIColor class]]) { // Not Memeber NSLog(@"Not Memeber"); }else { NSLog(@"Not Memeber"); } if ([imgView.image isMemberOfClass:[UIImage class]]) {// Memeber NSLog(@"Memeber"); }else { NSLog(@"Not Memeber"); }

[Scooter]

isKindOfClass will also return YES if the object is an instance of a given class. In other words isMemberOfClass is a subset of isKindOfClass.