NSLog returning null instead of string

Question

NSLog is returning the output 'Null" instead of a string that I would have expected. I suspect that this is a problem with private instance variables and such, but since I am not familiar with Object-oriented programming I cannot determine the cause.

//The viewDidLoad method in MainGameDisplay.m:
- (void)viewDidLoad
{
    [super viewDidLoad];
    Engine *engine = [[Engine alloc] init];
    [engine setPlayerName: viewController];
}

The string is entered by a UITextField, the property being

//ViewController.h
 @property (strong, nonatomic) IBOutlet UITextField *PlayerNameTextView;

The method works fine and returns the correct string if [engine setPlayerName: self] is placed into ViewController, but anywhere outside the location that *PlayerNameTextView is causes this problem.

//Engine.m
@implementation Engine
{
    ViewController *firstPage;
}

NSString *Player;

-(void) setPlayerName: (ViewController *) name
{
    Player = [[name PlayerNameTextView] text];
    NSLog(@"%@", Player);
}

And `Player` is declared in the implementation, which makes it some sort of a C global or static, I think. So I don't know how you expect to reference it elsewhere. — Hot Licks, Nov 06 '12 at 02:43
Set a breakpoint right before your NSLog and I suspect you'll see "`Player`" truly **is** null. Also, please follow objective C convention and start your variables with lower case letters (e.g. "`player`", not "`Player`"). — Michael Dautermann, Nov 06 '12 at 02:58
You might also want to NSLog "name", at the same time that you log "Player". — Hot Licks, Nov 06 '12 at 03:30

score 0 · Answer 1 · answered Nov 06 '12 at 02:56

0

NSLog return type is void as you can see in it's documentation. There is no reason to expect any return value for a call to it, since it does not return anything.

answered Nov 06 '12 at 02:56

Maurício Linhares

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By "return", I think @Sina is saying the console output is stating "``". – Michael Dautermann Nov 06 '12 at 03:00

boxel · Answer 2 · 2012-11-06T16:45:15.897

0

Make sure that 'name' is properly initialized. Try putting an assert(name != nil) right before the NSLog. Or better yet, set a breakpoint at the NSLog and inspect the variables.

Another suggestion: Why not make the method -(void) setPlayerName:(NSString*)name? This is more straightforward than passing around pointers to view controllers, and would be easier to debug.

edited Nov 06 '12 at 16:45

answered Nov 06 '12 at 03:06

boxel

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Better to make sure that "name" isn't nil. We already know that "Player" is nil, and assert(Player != nil) adds no information. – Hot Licks Nov 06 '12 at 03:32
This can't be the reason because if I run setPlayerName in ViewController itself, the program works perfectly. – PappaSmalls Nov 06 '12 at 08:31

NSLog returning null instead of string

2 Answers2