Question

I am new to Iphone programming. Please correct me where am I going wrong.

I have two viewcontrollers

viewcontroller1 viewcontroller2

In viewcontroller1,

-(IBAction) getQuestions:(id)sender
{
    NSLog(@"In get questions..");

    [[self viewcontroller2] initWithData:userInfo];

    [self presentModalViewController:viewcontroller2 animated:YES];

    [quesions autorelease];
}

In viewController2 I have the following code.

    -(id)initWithData:(NSMutableDictionary*)data
    {   
        self = [super init];

        if(self)
        {
        userInfo = [[NSMutableDictionary alloc] initWithDictionary:data];
        }

        return self;
    }



 -(IBAction) getQuesionAfterPopUp:(id) sender
{
    NSLog(@"In get question..After popup...%@",userInfo);

}

For some reason “userInfo” is null. Why is it null even after using init with data.

Answer 1

You didn’t initialize correctly, therefore the instance variable userInfo is not accessible.

Initialization should look like this:

- (id)initWithData:(NSMutableDictionary *)data 
{
    self = [super init]; // 'self' and it's instance variables are accessible at this point ...
    if (self) 
    {
        userInfo = // etc...
    }
    return self;
}

You might want to read up on this link for more information on how to implement designated initializers. Especially focus on the topic Implementing an Initializer.