Can't declare another window

Question

I'm trying to declare another window in MyThing.m

@property (nonatomic, strong) UIWindow *window;

But get this error

Illegal redeclaration of property in class extension "MyThing" (attribute must be 'readwrite', while its primary must be 'readonly')

If I rename window to something else, it is OK. Why is that? Is window meant to be declared once in the AppDelegate.h ?

You already have a property named `window`. You can't add a 2nd. — rmaddy, Jul 12 '14 at 17:50
@rmaddy but the window is declared in AppDelegate.h, while here I declare in MyViewController.m, is that not acceptable too ? — onmyway133, Jul 12 '14 at 18:01

score 3 · Accepted Answer · answered Jul 12 '14 at 18:18

I figure out the problem, it has nothing to do with the window property declared in AppDelegate.h

The problem is MyThing conforms to UIApplicationDelegate, and UIApplicationDelegate protocol declare a property

@property (nonatomic, retain) UIWindow *window NS_AVAILABLE_IOS(5_0);

So we must do either of these

MyThing.h (like AppDelegate.h does)

@interface MyThing : NSObject <UIApplicationDelegate>

@property (nonatomic, strong) UIWindow *window;

@end

OR

MyThing.m (synthesize the window property declared in protocol)

@implementation WYNAppDelegate

@synthesize window;

@end

1 Answers1