iOS: Methods and Functions

Question

I'm new to Objective-C, so I may be way off...

I have this in my 'viewDidLoad' method:

NSArray *myArray;
NSString *cow = @"Cow";
NSString *pig = @"Pig";
NSString *frog = @"Frog";
NSString *sheep = @"Sheep";
myArray = [NSArray arrayWithObjects: cow, pig, frog, sheep, nil];
randomNumber.text = [myArray objectAtIndex: arc4random() % (4)];

I want to make this its own method, so I can get a random animal any time I want...but I need this to happen when the program starts. How do I access a method like this?

I may be way wrong, so I'm open to suggestions, corrections, and anything you think is helpful.

Like this:

- (void)generateAnimal{
    NSArray *myArray;
    NSString *cow = @"Cow";
    NSString *pig = @"Pig";
    NSString *frog = @"Frog";
    NSString *sheep = @"Sheep";
    myArray = [NSArray arrayWithObjects: cow, pig, frog, sheep, nil];
    randomNumber.text = [myArray objectAtIndex: arc4random() % (4)];    
}

Also:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self generateAnimal;


}

Henri Normak · Accepted Answer · 2012-01-29 20:48:34Z

3

As Sagi mentioned before, in this case [self generateAnimal]; would have the wanted effect. In general Objective-C (as any other object oriented language) attaches methods to classes/instances, so you can only call them on existing instances. (Obviously there are class methods etc, but more abstractly speaking)

Objective-C wants you to enclose these calls to methods in square brackets ([ ]), as seen both in Sagi's answer and in your own example ([super viewDidLoad]). All the calls follow this pattern [target method: parameter]. Hope it makes sense, just wanted to add a bit of context to Sagi's answer.

answered Jan 29, 2012 at 20:48

Henri Normak

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Mundi · Accepted Answer · 2012-01-29 20:51:15Z

1

[self generateAnimal]; //would work great :)

edited Jan 29, 2012 at 20:51

Mundi

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answered Jan 29, 2012 at 20:41

Sagi

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4 Comments

Kevin Brown Over a year ago

Ah. The method has to be before when it is called?

Kevin Brown Over a year ago

PS: Is there a better way to make an array of strings?

Sagi Over a year ago

No, your code is just dandy, except you didn't enclose your method in square braces "[ ]".

Kevin Brown Over a year ago

Here's another quick question: How do I keep it from picking a random animal that is the same as a current animal? Doing this with only four variables makes it pretty likely that the same animal could be picked several times in a row.

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