Question

Pls help me with this:

The AppDelegate has an argument called “user”:

@interface AppDelegate : UIResponder <UIApplicationDelegate>
{
    User *user;
}
@property (nonatomic, retain) User *user;

and I init the user instance in the frist viewController:

User *userInfo = [[User alloc] initWithRealName:realName UserId:userId]; 

and set the user to AppDelegate’s:

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
appDelegate.user = userInfo;

In the second viewController, I can get the use’s realName,there is no problem:

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSString *realName = appDelegate.user.realName;

But when I push to another viewController,and I want to get the user’s realName like just now,
but there is an error:EXC_BAD_ACCESS:

AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
User *user  = appDelegate.user;
NSLog(@"I am in noticeDetailViewController:%@",user.realName);***//ERROR***

And I want to know why? and how to fix this error.

Thanks!

User.h & User.m

@interface User : NSObject
{
    NSString *realName;
    NSString *userId;
}

@property (nonatomic, retain)NSString *realName;
@property (nonatomic, retain)NSString *userId;
- (id)initWithRealName   :(NSString *)realNameArgument UserId :(NSString *)userIdArgument;
@end

@implementation User
@synthesize realName,userId;

- (id)initWithRealName   :(NSString *)realNameArgument UserId :(NSString *)userIdArgument 

{
    self = [super init];

    if (self)
    {
        realName = realNameArgument;
        userId   = userIdArgument;       
    }
    return self;
}

- (void)dealloc
{
    [super dealloc];
    [realName release];
    [userId release];
}

@end

Answer 1

AppDelegate does not retain user, so it gets deallocated before you try to access it in:

NSLog(@"I am in noticeDetailViewController:%@",user.realName);***//ERROR***

So Change AppDelegate by creating a retained property:

@interface AppDelegate : UIResponder <UIApplicationDelegate> {
// ...
@property (retain, nonatomic) User*user;
// ..

And don’t forget to synthesize it.

Also change the init method of user to:

- (id)initWithRealName:(NSString *)realNameArgument UserId:(NSString *)userIdArgument
{
    self = [super init];
    if (self) {
        self.realName = realNameArgument;
        self.userId   = userIdArgument;       
    }
    return self;
}