What is the class NSCFNumber in iOS 4.1?

问题

After successfully acquiring a picture from the iPhone camera on iOS 4.1, you can use the key

@"UIImagePickerControllerMediaMetadata"

to return information about the picture. One of the keys in that dictionary is

@"Orientation"

From my experimentation, Portrait and Upside down are 6 and 8 respectively, and the landscapes are 1 and 3. Look at this code:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    NSDictionary *metaData = [info objectForKey:@"UIImagePickerControllerMediaMetadata"];
    id orientation = [metaData objectForKey:@"Orientation"];
    NSLog(@"Class: %@",[orientation class]);

The NSLog says "Class: NSCFNumber"

I need to compare this object's value to determine how to proceed. Landscape is 1 or 3, portrait is 6 or 8. I'm not sure what to type orientation as or what to call on it. NSNumber and NSInteger always tells me I'm making integers from pointers without casts.

Thanks for your time!

回答1:

This is telling you that orientation is a instance of NSNumber. Technically, NSCFNumber is a private subclass of NSNumber, but that is an implementation detail which you don't have to worry about. To get the integer value you would call

[orientation integerValue]

回答2:

NSNumber is a class cluster. NSCFNumber is a concrete, "private" implementation of a class in that cluster. Just use the returned value like you would an NSNumber object.

来源：https://stackoverflow.com/questions/4357063/what-is-the-class-nscfnumber-in-ios-4-1

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iphone

ios

nsnumber