How to cast from Object 1 to Object 2 in Objective C

Question

How can I cast an Object to Person to access its property something like

((Person)self.dataObject).firstName;

except that clang doesn't accept this syntax :

DataViewController.h

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    self.dataLabel.text = ((Person)self.dataObject).firstName;
}

DataViewController.h

#import <UIKit/UIKit.h>

@interface DataViewController : UIViewController
@property (strong, nonatomic) IBOutlet UILabel *dataLabel;
@property (strong, nonatomic) id dataObject;

@end

Person.h

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property NSString* firstName;
@property NSString* lastName;

@end

max_ · Accepted Answer · 2014-05-03 16:52:26Z

3

You're not casting it as a pointer to an object. Instead you should be casting it as follows:

((Person *)self.dataObject).firstName;

edited May 3, 2014 at 16:52

answered May 3, 2014 at 14:33

max_

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1 Comment

jscs Over a year ago

The lack of the asterisk does not make a type "primitive". Pointers, in fact, are primitive types themselves, but objects, which are not, are only accessed via pointers in ObjC.

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