Cannot find protocol declaration for 'NSPasteboardWriting'

I am getting this error

Cannot find开发者_如何学JAVA protocol declaration for 'NSPasteboardWriting'

i have created the class

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>

@interface ErrorLog : NSObject<NSCoding, NSPasteboardWriting, NSPasteboardReading> {

}

@end

Can any one tell me that whether i am missing some header file or whats the reason for that?

NSPasteboardWriting is Available in Mac OS X v10.6 and later. check your project setting(Base SDK).

Import the header file in which NSPasteboardWriting and NSPasteboardReading protocols are declared. Also make sure you have the protocols in the class specified.