Delegate as external class in Objective-C

@interface Control1Delegate : NSObject <UITextFieldDelegate> {
}

- (BOOL) textFieldShouldReturn:(UITextField *)textField;

@end

#import "Control1Delegate.h"

@implementation Control1Delegate

- (BOOL) textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES;
}

@end

@property (nonatomic, retain) IBOutlet Control1Delegate *control1delegate;