Question

I’m trying to create a string (foo2) which will have all the string object in the fooArray. I don’t understand why the below posted code doesn’t do that for me.

- (void)viewDidLoad
{ 
    [super viewDidLoad];
    NSString *foo =@"This is just a test";
    NSArray *fooArray = [foo componentsSeparatedByString:@" "];

    for(int i=0; i < fooArray.count; i++)
    {
        _foo2= [_foo2 stringByAppendingString:[ fooArray objectAtIndex:i]];
    }

    NSLog(_foo2);
}

Answer 1

I’m guessing it’s because you are not initializing _foo2 anywhere before viewDidLoad runs. And since _foo2 hasn’t been initialized and is still a nil pointer, every time you send the stringByAppendingString: message to it, the result is still nil.

You can fix this by initializing _foo2 to a new NSMutableString object before your loop.

- (void)viewDidLoad
{ 
    [super viewDidLoad];
    NSString *foo =@"This is just a test";
    NSArray *fooArray = [foo componentsSeparatedByString:@" "];

    _foo2 = [[NSMutableString alloc] init];
    for(int i=0; i < fooArray.count; i++)
    {
        _foo2= [_foo2 stringByAppendingString:[ fooArray objectAtIndex:i]];
    }

    NSLog(_foo2);
}