Pick random element of NSArray in Objective-C

Question

Possible Duplicate:
Picking a Random Object in an NSArray

I have have an array in Objective-C with strings:

NSArray *tips;
tips = [NSArray arrayWithObjects:
       @"Foo",
       @"Bar",
       @"Baz",
       nil];

I want a method that takes a random item from the array, and returns it. Is there a method, or how can I write one myself? Thanks.

Answer 1

Use this code:

uint32_t rnd = arc4random_uniform([tips count]);

NSString *randomObject = [tips objectAtIndex:rnd];

EDIT: While working on my project i decided to create a category for NSArray. It's very simple but i found it useful.

Here are the files:

NSArray+Random.h

#import <Foundation/Foundation.h>

@interface NSArray (Random)

- (id)randomObject;

@end

NSArray+Random.m

#import "NSArray+Random.h"

@implementation NSArray (Random)

-(id)randomObject {
    NSUInteger myCount = [self count];
    if (myCount)
        return [self objectAtIndex:arc4random_uniform(myCount)];
    else
        return nil;
}

@end

Then in the current example you use it like this:

NSString *randomObject = [tips randomObject];

Using category has another advantage: when you decide to change your way of selecting random objects in your app you just modify the randomObject method.